Serena Williams bypassed any clay-court tuneup tournaments ahead of the French Open, so her first match at Roland Garros will be her first competition since the U.S. Open.

Naomi Osaka won the U.S. Open and is sitting out the French Open, which starts its 15 days of main-draw action Sunday after being postponed in May because of the coronavirus pandemic.

Dominic Thiem also won the U.S. Open and decided to rest at home for a bit before heading to Paris.

Simona Halep skipped the trip to New York's hard courts altogether and has been playing exclusively -- and extremely well -- on clay since tennis resumed after its pandemic hiatus.

Rafael Nadal sat out the U.S. Open, too, but he only has played three matches on his favourite surface in all of 2020, hardly the sort of run-up to Roland Garros the King of Clay is used to.

"A completely special year," he said after a quarterfinal loss in Rome last week, "and unpredictable year."

And Novak Djokovic? He travelled to the United States, won the Western & Southern Open and experienced a tumultuous exit from the U.S. Open via disqualification, then flew back halfway around the world and won the Italian Open, which he probably considers perfect preparation for the year's last Grand Slam tournament.

"Well, it is unusual to be in these kind of circumstances, but at the same time, we are -- I am, and I know most of the players are -- thankful that we have a chance and opportunity to play and compete and be on the tour," said Djokovic, who will be seeded No. 1 at the French Open.

He is bidding for a second title there and 18th Grand Slam trophy overall, which would move him within two of Roger Federer's record for men and one behind second-place Nadal. (Federer is sidelined for the rest of the season after two operations on his right knee.)

"It's just very close after an exhausting month of tennis in (the) States on a different surface (to) come back and play ... on a different surface, different continent," Djokovic said. "It's very challenging."

All players needed to make their own decisions about how to approach this once-in-a-lifetime -- let's hope so, anyway -- year and the coronavirus-altered tennis calendar, with the quick switches from North America to Europe and from hard courts to clay that no one is used to managing quite this way.

As Johanna Konta, a three-time Grand Slam semifinalist now ranked 13th, put it: "It is a very different, very strange, very unorthodox kind of mini-season for us."

With the French Open beginning exactly two weeks after the U.S. Open ended, the hindsight-is-20/20 answers to various key questions everyone needed to confront eventually will present themselves on the courts.

"You have to play your cards smart there, I guess," said Thiem, the runner-up to Nadal in Paris the past two years.

Enter just one of the two back-to-back majors?

If so, which?

Try to be good on both hard courts and clay?

If so, what's the best way to make the transition, which requires adapting to different footwork, above all, and adjusting in-match strategy, because the slower clay requires more patience during points and dulls the effect of a speedy serve?

"It doesn't matter how good you are," said Svetlana Kuznetsova, who skipped the U.S. Open (which she won in 2004) and is entered in the French Open (which she won in 2009). "Nothing replaces match preparation."

There also are those not playing in New York or Paris, including Federer, 2019 French Open champion Ash Barty and 2019 U.S. Open champion Bianca Andreescu.

"I have no regrets with my decision. Of course I'm sad that I didn't play (in the U.S. Open). It's normal. But I feel like my decision was great for the health issue and to feel, like, relaxed inside," said Halep, who comes into a tournament she won in 2018 for one of her two Grand Slam titles as a favourite, especially with the top-ranked Barty and No. 3 Osaka absent. "I always take these decisions just related to myself, how I feel mentally and stuff like this. So it's all good."

Halep enters on a 14-match winning streak, including clay-court titles in Prague last month and Rome last week.

Could all of the time Halep spent on clay be an advantage for her against players who trained and played on hard courts?

"Yes and no," was Halep's answer.

"Yes, because I had the chance to practice on clay only, and no, because I didn't have official matches," she said. "So both sides, I think, have an advantage, if we know how to (use) it."

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AP Tennis Writer Fendrich reported from New York; AP Sports Writer Dampf reported from Rome.