Nadal, Federer race for No. 1 makes this fall much-watch tennis

Tennis usually stumbles during the fall season, offering fans and viewers a product that could easily be mistaken for television reruns.

The problem is understandable. By mid-September, players are plane- and-battle-weary. Small aches are ballooning into hurts. While the lure of lucre in Asia is powerful, the culture shock for those who can't bring along the entire family and staff and book an entire floor in a hotel, is significant. The Grand Slam dust has settled, the pecking order decided.

Take 2016. Roger Federer, Rafael Nadal, Serena Williams, and Maria Sharapova all missed the entire Asian swing, as well as the ATP and WTA year-end championships. It was an exceptionally rough year even by the recalibrated standard we often apply to the fall.

As fall rolls on, conversation usually turns to why tennis needs a longer off season. Softer tennis balls. Faster courts. String police.

But that doesn't seem to be the case in 2017.

This year, the storylines will be different and potentially riveting. Serena Williams remains out on maternity leave, but the other stars who were MIA last year are in, as are the women jockeying to claim the prestigious year-end No. 1 ranking.

The WTA offers a few opportunities to score big this time of year, with one Premier, one Premier 5 and one Premier Mandatory-level event before the year-end championships begin the last week of October.

The ATP has four ATP 500 tournaments and two ATP 1000 Masters tournaments on tap before the ATP World Tour Championships take place in London in mid-November.

Here are the players -- and themes -- most likely to pique our interest for the year of the season:

Rafael Nadal's drive to complete a career year

Rarely is a rankings picture as clear as this one: Top-ranked Nadal leads rival No. 2 ranked Roger Federer by a shade under 2,000 ATP rankings points, with neither man having any points to defend the rest of the year. But this pair of over-30 icons (in Federer's case, well over 30) has sworn off chasing rankings and pushing themselves beyond their respective comfort zones. Neither man has entered the rankings-points rich Paris Masters.

Nadal in particular has been stressing his commitment to enjoying his daily labors. "I'll tell you, for me what is more important, more than winning Slams, is be happy," Nadal said, after dismissing Juan Martin del Potro from the US Open semifinals. "I am happy if I am healthy, and happy if I feel competitive in the most of the weeks that I am playing, and that's what happened this year."

We might have one or two more Federer-Nadal clashes -- one of them on Federer's home turf in the Basel ATP 500. Nadal will go about trying to complete the only unfinished business on his career resume: win a first fall Masters title and the year-end ATP championships.

Nadal has qualified for the year-end finals 12 times, but he missed the event entirely with injury five of those years. He probably won't miss it this year. A win in Shanghai, and at the finals in London, could make this his greatest year ever.

Roger Federer's push to finish strong

Did anyone else feel that Federer's post-Wimbledon fade was a little alarming?

It seems ungrateful to think in those terms, but that's the cruelty of sports. No matter how magical his game or indomitable his spirit, Federer is 36 years old. At some point, the engine can't produce the same horsepower it once did. Federer lost to 20-year-old Alexander Zverev in Montreal, pulled out of Cincinnati with a tweaked back, then fell to Juan Martin del Potro at the US Open in the three events he played after Wimbledon. It's time to regroup.

The encouraging thing for Federer is that Asia loves him, and he loves Asia back. He was in three finals, winning two, when the ATP World Tour Finals were held in Shanghai. He also won one a Masters 1000 in that city. Federer has an outstanding record at the ATP tour record in London. He's 6-4 in finals, and has been in at least the semifinals every year that he's qualified.

Federer has set a high bar for himself in the fall. He doesn't have to clear it, but it would be encouraging to see him finish the year strong and healthy. Why not shoot for glory at 37?

Maria Sharapova's hopes to crash the rankings

It's been a pretty rough ride so far for the 30-year-old Russian who's trying to rebuild a career tainted by a recent 15-month doping suspension.

Sharapova, who has boosted her ranking up from No. 103 since her return in mid-April, will play the Premier Mandatory China Open and the International level event in Tianjin. She's likely to find the glare of the spotlight less harsh in China, which may leave her more relaxed. Two good results in Asia would boost Sharapova's confidence and leave her well-positioned for next season.

Sharapova has yet to show she can regain the consistency and focus that earned her a career Grand Slam. She has missed a lot of time and suffered numerous injuries. Willpower and competitiveness will take you far, but not all the way.

The WTA race for No. 1 will almost surely go down to the wire

At the moment, fewer than 500 rankings points separate the top four WTA performers, with No. 1 Garbine Muguruza holding a slim 75-point lead over No. 2 Simona Halep. The really weird thing? Halep isn't really considered the woman most likely to displace Muguruza at the top at year's end. That probably would be former No. 1 Karolina Pliskova, who is down to No. 4. But current No. 3 Elina Svitolina has been a dark horse all year. Wouldn't it be just like the WTA this year if she ended up No. 1?

The Beijing Premier 5 alone is worth 1000 points, while the myriad lesser events offer 280 points (for a winner) on up. There are 12 tournaments to go, including those ongoing. Look for a lot of wild action in the coming weeks.