-- It's that time of the season. Yes, the injuries are piling up on the star players, which makes for a lot of question marks as the year winds down. With that in mind, here are a few pressing questions:
Given all his injuries and his commanding lead in the rankings, should Novak Djokovic consider withdrawing from the rest of the season?
Nic Atkin: It may be a sensible idea, but don't think for a second that Djokovic will contemplate it. The world No. 1 said he "missed" tennis after getting a couple of free passes on his way to the fourth round of the US Open. If getting two walkovers fills him with longing to pick up his racket, then skipping three months would be unbearable.
Peter Bodo: Absolutely not, unless those injuries are more severe and require more intensive rehab than it appears. Djokovic's season is already made. He is ideally positioned to keep his stranglehold on the game, and besides, he does have professional obligations to the tour as the No. 1 player and an enthusiastic spokesperson.
Greg Garber: Absolutely not. Look at the past four years, when Djokovic finished the season as the world No. 1 three times and No. 2 once. In each instance, he won the ATP World Tour Finals. If it ain't broke, don't fix it.
Johnette Howard: Yes. He seemed to be running on fumes by the US Open and has been cryptic about personal issues that were also troubling him. It hasn't been easy to be dominant as long as he's been. A break could be restorative.
Melissa Isaacson: Yes, he should certainly consider taking off the rest of the season. But he has always recognized in the past when his body needed a rest, and commanding lead in the rankings or not, his judgment should not be questioned now.
With the WTA Finals coming up, how important is it for Serena Williams to get healthy and win it again?
Atkin: Serena should target the Australian Open as her comeback event, not the WTA Finals. Breaking Steffi Graf's major record will be a far bigger incentive than reigning in Singapore. With her 35th birthday just a few days ago, Serena needs to be smart about her schedule and build her season around the Slams.
Bodo: If somehow Williams is in a position to reclaim the No. 1 ranking, it would be a shame for her not to make the effort. It would certainly add to her legacy. But since that's an unlikely scenario, it's only important in that making a powerful year-end statement would give her rivals a lot to think about over the winter break and convince fans and pundits that we can expect a lot more from her next year.
Garber: Important. As Pam Shriver told me recently, at Serena's age (35), she can't simply play her way into Slams after a period of inactivity. Last year, she shut down after the US Open and looked rusty in Melbourne in January. She needs to bring some momentum into 2017.
Howard: It's vital for her to get healthy. I have doubts she'll even show up for the WTA Finals based on her recent statements that she's tired of playing hurt, and I don't blame her. But if she does heal and show up, she might as well win it.
Isaacson: Not important at all. Serena has nothing to prove, and only the all-time Slam singles record is worth going after at this point. And frankly, if she ends her career still tied with Steffi Graf at 22 majors, it should not affect her claim on greatest of all time.
What do we realistically expect from Roger Federer when he returns to tour?
Atkin: Sad as it is to comprehend, Federer could well begin his lap of honor next season. He has defied the sands of time for long enough, but his body is finally failing him. He just doesn't have enough in him to win an 18th major, though he will entertain us all as usual by threatening the possibility with a run to the Australian Open quarterfinals.
Bodo: The greatest gift Roger will bring to the tour next year is his presence. He just adds so much value to an event, because like Serena Williams, he is a true transcendent superstar. If he's fully fit, I expect Federer to be about 80 percent of "full-flight" Federer, which is a lot of "Geez, isn't this great?" tennis and wonderful for the game. He'll probably get a lot more Sundays off, but who knows: Maybe he'll produce one, final, career-capping major performance.
Garber: More of what we've seen in recent years. No Grand Slam titles, but it makes sense to pencil him in for some of those titles he won in 2015: Brisbane, Dubai, Basel and Halle.
Howard: More of the same: Glimpses of brilliance and moments where his age and vulnerabilities show enough to prevent him from sustained greatness throughout the year. That's a lot to ask from him now, even for an entire two-week major tournament.
Isaacson: This was his first serious injury, and he is obviously being conservative in his recovery. There is no reason, even at age 35, to think he can't eventually get back to the level he was at with his semifinal finish at Wimbledon.
How much pressure should Andy Murray be putting on himself to heal up and win a first ATP Finals in his home country?
Atkin: Murray and the ATP Finals have never really been a good fit at the O2 Arena in London. Unlike last year, he won't have a Davis Cup final to prioritize. With Federer absent and Djokovic out of sorts and healing up himself, Murray has a chance to tick another accomplishment off the list.
Bodo: I don't think the ATP World Tour Finals means a great deal to Murray, certainly not as much as any major, but the ATP probably is getting tired of sitting around with its fingers crossed, hoping he pulls it off. It would certainly be a PR coup, good for the game in general, and it would add a significant resume item to a CV that is long on runner-up finishes at the biggest events.
Garber: To be honest, I don't think he cares all that much. In seven previous appearances, he's never won the year-ender, going out in round-robin play four times, including the past two years.
Howard: No pressure to win. He's already had a good year with his Wimbledon title and Olympic gold-medal run. He has seemed more exhausted than seriously ailing, so he's definitely a threat to win it all in London. He certainly seems to play inspired tennis there.
Isaacson: Even when Murray says he doesn't feel outside pressure to win, you can read his own desire with every grimace. If he is close to 100 percent, you can bet he'll be in London on Nov. 13. Whether he should be placing that pressure on himself hardly matters.