Novak Djokovic stood stoically, as still as a stone -- was it another strong take on the mannequin challenge? -- and the smoke billowing at Londons O2 Arena began to engulf him.Before his opening match at the Barclays ATP World Tour Finals against Dominic Thiem?on Sunday,?Djokovic stood there and briefly closed his eyes, and you have to wonder whether, even for a moment, he wished he could make himself disappear.For four of the past five seasons, Djokovic has finished as the No. 1-ranked player. He could still make it five out of six with a victory in this eight-man event, something that, based strictly on history, wouldnt be terribly surprising; he has won each of the past four editions of this tournament.After losing the No. 1 last week to Andy Murray, the world No. 2 essentially needs to go one step further than Murray in London.With Djokovics uneven 6-7 (10), 6-0, 6-2 victory over the 23-year-old Thiem, it would be a little too easy to declare Djokovics glorious run of dominance over. But its not irresponsible to wonder whether his shelf life at the top has a rapidly advancing expiration date.The recent signs, including this manic match with Thiem, arent particularly good. Lets just say that for Djokovic, the end of the season cant come fast enough.The frustrations were still evident Sunday, even after a smooth final two sets. In his postmatch news conference, Djokovic had a heated exchange with reporters when the world No. 2 found himself on the defensive answering questions about his recent bouts of temper. Heres how it went down:Question: Back to the end of the first set, we saw you similarly venting your frustration at Roland Garros, throwing your racket. Does it concern you one day that will cost you dearly? If it hit someone ...Djokovic: You guys are unbelievable.Q: Why is it unbelievable?Djokovic: Because youre always picking these kind of things.Q. If you keep doing these things ...Djokovic: I keep doing these things? Why dont you get suspended then?Q. You were close, werent you?Djokovic: Im close? Im still not suspended, so if Im not close, Im not close.Q: If that ball had hit a spectator, it could have been serious.Djokovic: It could have been, yes. It could have snowed in O2 arena, as well, but it didnt.Q: Youre not concerned about your mindset?Djokovic: Im the only player that shows his frustration on the court? Thats what you are saying?Q: Youre one of the top-ranked players in the world.Djokovic: So?Just five months ago, Djokovic seemed invincible. He won the Australian Open, the rare Indian Wells-Miami double and then the French Open, completing his career Grand Slam. That was his 12th major singles title, and that noise you heard was the crunching of all-time numbers.How long before the 29-year-old Serb caught his long-time rivals, Roger Federer (17) and Rafael Nadal (14)? Since taking three Grand Slams in 2011, Djokovic had won an astounding 11 of 22 majors up to that point. That trajectory would vault him past Nadal -- and Pete Sampras, too -- by the end of 2017. Federer would be in his sights by 2018.And then Djokovic -- perhaps in retrospect it was inevitable -- came back to the field. He lost to Sam Querrey in the third round at Wimbledon, Juan Martin del Potro in his first match at the Rio Olympics and Stan Wawrinka in the US Open final.After falling to Marin Cilic in the quarterfinals of the BNP Paribas Masters earlier this month, Djokovic unblinkingly tackled the elephant in the room: his disturbing and dramatic loss of confidence on the court.A lot of things, a lot of emotions went through my mind and body in the last two years, Djokovic said, with the things that I was blessed to achieve, obviously, and the career Grand Slam this year. But it took a lot out of me, and it has put some things in perspective and, obviously, raised some questions in which direction I want to go to.So Im in the process at the moment, and its going [to] obviously take some time really for me to redefine all these things.Against Thiem, it took a 69-minute first set to accomplish that reset.Djokovic was tentative in that frame and Thiem was consistently fiery. Then, after earning three set points in the tiebreaker, Thiem succumbed to nerves, pounding back-to-back double faults and a tight backhand into the net. Finally, on his seventh set point, he whipped a forehand winner.At one point, Djokovic lost his racket and his legendary balance, winding up on his behind, then offered a thin smile -- maybe it was actually an embarrassed grimace.Whatever it was, it returned him swiftly to full power.As Federer and Nadal have both learned, the 30th year of a professional tennis players life can be a difficult one. After winning his 16th major, at the 2010 Australian Open at the age of 28, Federer has won only one since. Nadal had just turned 28 when he won the 2014 French Open -- and he hasnt won one since. Sampras, too, won one major after turning 29.Djokovic celebrated his 29th birthday just before the French Open. He has struggled with physical and mental issues ever since winning that cherished, life-changing title.This season-ending tournament offers a revealing glimpse into his psyche.Look, in the end of the day, I have to get to that state of mind where Im able to perform as well as I want to match after match, Djokovic said at the Paris Masters. I was not able to find that level for last couple of months.But Im still here, and I feel like Im on the right path. Im in a better state of mind than I was some time ago. Thats all Im thinking about right now.Jake Marisnick Jersey . Just as Montreal was settling into the first full working week of a new year, the Impact announced the appointment of their new head coach. Yuli Gurriel Astros Jersey ., for the next three years with the signings on Monday of Daryl Townsend and Michael Carter. http://www.baseballastrosproshop.com/jr-richard-astros-jersey/ .ca looks back at the stories and moments that made the year memorable. Robinson Chirinos Astros Jersey .J. -- Josh Cribbs was in the Pro Bowl in February and out of a job six months later. George Springer Astros Jersey . Howard Ganz, an MLB lawyer, said in a letter to U.S. District Judge Edgardo Ramos that Rodriguezs claims do not come "remotely close" to what is needed to overturn an arbitration decision in federal court.After years of lopsided results in Denvers favor, the rivalry between the Broncos and the Oakland Raiders appears to be heating up again.Both teams are 6-2 and tied atop the AFC West heading into Sundays matchup in Oakland, the 111th meeting between the division rivals. Denver has regularly gotten the better of the Raiders in recent years, winning eight of the last nine since 2011, and the Broncos are 26-7 overall in divisional play over the last five years, the best winning percentage against divisional foes in the NFL in that span.But the Raiders have served notice that they are a different team this season, with quarterback Derek Carr leading a dynamic offense that is averaging 401.6 yards per game, ranked fifth in the league. In last weeks overtime win over Tampa Bay, Carr became the third player in NFL history to throw for at least 500 yards passing (513), four touchdowns and zero interceptions in a game.Hes playing at a really high level, Broncos linebacker Shane Ray said. With all the talk thats been going around the league, with how hes been playing and his number of pass attempts through the game, hes a quarterback that you definitely have to have pressure on or hell pick you apart. Theyve been a really good balanced team as far as running the ball and passing the ball. Derek Carr is definitely making an impression on the league right now.Carr has helped turn Amari Cooper and Michael Crabtree into one of the most feared receiving tandems in the league. Cooper had 12 catches for 173 yards, both career highs, against Tampa Bay and Crabtree has six touchdown catches, tied for the league lead.Hes doing some good things this year, Broncos safety T.J. Ward said of Carr. He seems to have a handle of the entire offense and his receivers are catching some great passes from him. Theyre clicking right now.The upward trajectory for the Raiders, who would match their win total from last season with a victory Sunday, has coincided with the arrival two years ago of coach Jack Del Rio, who was the Broncos defensive coordinator before going to Oakland.Were obviously still learning, Carr said Where were at? Im not sure, but were in a good spot. Were heading the right way, but we still have a way to go as a football team.Del Rio said he senses something of a culture change among the Raiders.I think weve changed the mentality here in this building. Thats part of it, Del Rio said. Last year, we learned how to compete and this year were learning how to close plays, how to make the plays that need to be made to win.The Raiders and their high flying offense face a severe test against a Broncos defense that already has shown its mettle against some of the best quarterbacks in the league, beating ssuch stalwarts as Carolinas Cam Newton, Indianapolis Andrew Luck and San Diegos Philip Rivers, against whom the Broncos had three interceptions last week, including one that cornerback Bradley Roby returned 49 yards for a touchdown.ddddddddddddDenver leads the NFL in sacks with 26, and Super Bowl MVP Von Miller ranks second in the NFL with 8.5 sacks. In addition, no team in the league has scored more points off turnovers (80) than the Broncos.Carr said he considers Chris Harris Jr. and Aqib Talib, who will miss his second straight game with a back injury, the best cornerback tandem in the league. Bradley Roby replaced Talib last Sunday and was named the AFC Defensive Player of the Week.To have them on the same team, its ridiculous, Carr said. I think the world of them. When you study them, theyre very tight cover guys that are very smart. You can tell that they study. You can definitely tell that they know where their help is. They know how to communicate in the secondary, so I think theyre some of the best, not only in this league, but that weve ever seen together.The Broncos, meanwhile, are hoping to get more production out of their offense, which has struggled to achieve balance this season between the pass and the run, most especially since the loss of running back C.J. Anderson to a knee injury.Theres conversation all of the time about how are we balanced-wise? What is going on here? Broncos coach Gary Kubiak said. Like last week, you know youre out of whack. You have to go out there and make plays to win games. The key to balance is you have to run plays. We had fifty-something plays last week and we have to find a way to be more balanced as a group. You also have to do what the defense is telling you to do, too. Its a commitment and one that you have to hang on to, but at the same time, you have to stay aggressive in this league. You have to make plays.The Broncos have had injury issues in their backfield. Beyond Anderson, his replacement, rookie Devontae Booker, had some limitations in practice this week because of a shoulder injury suffered in last Sundays win over San Diego.Denver cornerback Kayvon Webster also had some practice restrictions because of a hamstring injury.Broncos linebacker Brandon Marshall could return this week from a hamstring issue after missing the San Deigo game, though he remains questionable.Raiders defensive tackle Stacy McGee (ankle) also has missed practice time this week after missing ast weeks game against Tampa Bay.Cornerback Sean Smith suffered a shoulder injury against Tampa Bay and has been limited in practice. ' ' '