The autumn air -- when it's not spewing thick, wet snow -- is exceptionally clean and crisp. Darkness falls early and Thanksgiving isn't far away. And, players on the ATP World Tour find themselves on unsteady legs, limping toward the finish line.
Say, what's that distinctive aroma?
It's Fed Time.
Roger Federer, at the age of 30 years and 3 months, is positioning himself for another powerful year-end push. Last year he -- not Novak Djokovic, Rafael Nadal nor Andy Murray -- won the Barclays ATP World Tour Finals. After winning his hometown tournament last week in Basel, Switzerland, for the fifth time, Federer seems pointed in the same direction.
Last Thursday, Nadal pulled out of the BNP Paribas Masters but did not cite an injury. Sunday, not surprisingly, Juan Martin del Potro also bailed from the Paris event. Like Rafa, he was probably looking ahead to the Dec. 2-4 Davis Cup final in Sevilla, Spain, that pits Nadal's Spanish team versus del Potro and Argentina. Even the No. 1-ranked Djokovic looked a little bit nicked up in losing to Kei Nishikori in the semifinals at Basel.
Federer? He's in typically fine form, seeded No. 3 in the bottom half of the Paris draw, where he could meet No. 2 seed Andy Murray in the semifinals of the year's last regular-season event.
Darren Cahill, who coached both Andre Agassi and Lleyton Hewitt to the No. 1 ranking and has spent quality on-court time with Federer, never ceases to be amazed.
"The guy's achieved so many records in the game, sometimes we still manage to overlook him," Cahill said earlier this week from Las Vegas. "Nadal and Djokovic passed him, and he could have taken it either of two ways. I think he took it the right way -- as a challenge to get better.
"He played some sensational tennis this year. Maybe not for the sustained periods we saw in 2004, 2005, 2006, but he was right there most of the year. He played some great clay-court tennis, probably better than he won in Paris . He was a swing away [against Djokovic] from reaching the final at the U.S. Open. He just keeps putting himself in good positions to win."
Federer has won a record 16 Grand Slam singles titles, and he's viewed by many as the greatest tennis player ever, but Cahill pointed out a telling statistic that not every casual fan knows. After playing nearly 1,000 career ATP matches (983, to be exact), Federer has never, ever retired from a match once he has walked onto the court. The older he gets, the more impressive that becomes.
"It's a tribute to his coaches and trainers," Cahill said. "Your body is your greatest asset and Roger works really hard on his offseason conditioning. He's kept up his speed on the court -- and his enthusiasm, too. That's one of the reasons you see him playing like this."
Federer began play in Basel with his lowest ranking (No. 4) since 2003, but didn't seem concerned. He said he hadn't done the math to determine how many points he needed to return to the No. 3 spot.
"My goal is trying to win when I'm playing the next few weeks," Federer said in Basel. "Clearly, after winning here [in 2010], semis in Paris with match points and winning London, I know I can do extremely well. And If I'm [Nos.] 3 or 4 at the end of the year, we'll see, but if I'm going to make a move I need to win tournaments."
Basel was the 68th career title for Federer and it ended a 10-month drought, going back to his season-opening victory in Doha.
"I'm feeling really fit and I'm ready for more," Federer said. "I'm very hungry and fired up."
Late in his career, Andre Agassi worked as hard as anyone in the offseason, running the hills near Las Vegas under the eye and at the urging of trainer Gil Reyes. It paid off nicely; Agassi won three of four Australian Open titles from 2000-03, the last two at the ages of 30 and 32. Federer has a famously grueling training routine in Dubai, usually in December and July. It's no accident that his last Grand Slam singles title came at the Australian Open, in January 2010, following one of those sessions.
Three different times, 2004, 2006-07, Federer won three majors in a single season. Nadal did it in 2010 and Djokovic this year, so those prized titles have been tougher to come by. Can Federer capitalize on some late-season momentum and take another title Down Under?
"Yeah," Cahill said without hesitation. "Certainly, it gets tougher and tougher as he goes along. This year he was very, very close. Clay in Paris, with Nadal, that's always going to be the toughest one. But the Aussie, Wimbledon and U.S. Open are three Slams where he can put himself into contention. I give him a chance to win one.
"And this year, the icing on the cake is the Olympics. Roger has two shots at Wimbledon. I'm sure that's a high priority."
Greg Garber is a senior writer for ESPN.com.