(CNN)It's rare for an elite athlete to publicly admit to shortcomings in his game, especially when the player isn't far removed from his or her prime.
Will the clay rescue Rafael Nadal? Can Serena Williams triumph in Paris?
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But following an upset loss to Fernando Verdasco at the Miami Open last month, Rafael Nadal -- who fell to his Spanish compatriot for the second time in a row after beating him on 13 successive occasions -- conceded something was awry.
"My game in general improved since a month and a half," he told reporters. "But at the same time, still playing with too much nerves for a lot of moments, in important moments, still playing with a little bit of (anxiousness) on those moments."
Now working in his favor, though, is the tennis circuit switching from hard courts to red clay, beginning with the traditional European curtain raiser in Monte Carlo.
Will the clay cure Rafa's ills?
It's one of five pressing questions as the clay-court swing -- which ends with the French Open -- got underway.
Will Rafa find form?
Injuries have been a mainstay in Nadal's career, that we know. But the knees weren't the issue in 2014.
Rather, he skipped the U.S. Open with a wrist complaint and dealt with a back problem that most notably hampered him in the Australian Open final. If that wasn't enough, he came down with appendicitis in the fall.
The lack of match action seemed to catch up with the 28-year-old at this year's Australian Open -- he lost to Tomas Berdych, who he had beaten 17 straight times -- and even at a small clay-court tournament in Buenos Aires in February, Nadal wasn't at his best, despite winning.
Then came a first reverse to Milos Raonic in Indian Wells and the defeat to Verdasco.
No wonder Nadal told Spanish television last week: "It's a clay court season where perhaps I am arriving in the worst form of my career."
The clay, though, and particularly the French Open, have always seemed to be the perfect tonic for Nadal.
Take last year as an example.
It was the first time in his career that Nadal hadn't claimed at least two European clay-court titles heading into Roland Garros -- and the one he did win, in Madrid, came courtesy of a retirement. Kei Nishikori was having the better of the finale before a back injury took its toll.
But Nadal proceeded to march to the French Open final, dropping one set, and ousted Novak Djokovic for a ninth crown in southwest Paris.
Should he repeat at the French, he'll become the first player in the Open Era to bag any major 10 times.
Will Halep win her first major?
Simona Halep won her first six titles in 2013. Last year she moved into the top 10 after winning two more and reaching a first grand slam final in Paris, extending now clay-court queen Maria Sharapova to a tight third set. Already this year, Halep bagged her biggest title in Indian Wells last month after successes in Dubai and China.
Now that's progress.
Going one better at the French Open, then, would leave few surprised.
After her successful stint in Indian Wells, Halep gave Serena Williams her toughest battle in Miami, forcing a third set prior to falling 7-5. Williams rarely loses or comes close to losing at her home tournament, having now grabbed eight titles.
World No. 3 Halep routinely clocks up highlight-reel points, is arguably the best counter-puncher in women's tennis and possesses a backhand that can produce a winner from virtually anywhere on the court.
"I'm actually a fan of hers," said Williams, who lost to the 23-year-old at the 2014 WTA Championships before taking revenge in the final.
"I really like her attitude on the court. I like how she gets pumped up. I like how she fights. I like how she plays. It's definitely a refreshing type of game."
Virginia Ruzici, Halep's manager, is the only Romanian woman to win a grand slam title at the 1978 French Open.
Can Bouchard rebound?
Plenty happened to Eugenie Bouchard last year, and maybe -- even for the apparently headstrong Canadian -- it was too much.
First there was a grand slam semifinal at the Australian Open, accompanied by the birth of the "Genie Army." She followed it up by making the French Open semifinals and she didn't stop there, getting to the final at Wimbledon.
The second half of the year was forgettable, as a mentally drained and physically hampered Bouchard won just nine matches.
The off-season also brought turmoil: Coach Nick Saviano cut ties with Bouchard, and nagging injuries have contributed to a 6-5 record.
The last of those losses came in her opener on the green clay of Charleston last week.
It has always appeared to be Bouchard's weakest surface, but we shouldn't forget that her first title came on clay in Germany a year ago in the week leading up to the French Open.
She'd sure love a spell of good health, too.
Which Serena shows up in Paris?
Of Williams' 19 grand slam singles titles, not many have come in Paris -- two to be exact.
Playing on clay neutralizes, to some extent, Williams' biggest weapon, her serve, and the world No. 1 is not as comfortable moving on the surface as others who've grown up on dirt.
Either side of winning her second title, there were first- and second-round exits.
Indeed, it's been Williams' longtime rival, world No. 2 Sharapova, who has surged on clay, winning the French Open in 2012 and 2014.
But for the first time in her career, Williams enters a European clay-court season undefeated.
Sharapova, meanwhile, is in a slump, losing in the fourth round in Indian Wells and her opening match in Miami against fellow Russian Daria Gavrilova, ranked 78 places below her.
Can Djokovic get over the hump?
Novak Djokovic, the men's world No. 1, has unquestionably been Nadal's biggest threat on clay in the last four years.
Since the start of 2011, Nadal leads their head-to-heads on clay but only marginally, 5-4.
None of the four victories have come at Roland Garros, however. Nadal topped Djokovic at the French Open in four sets in 2012, five sets in 2013 when a freak error by Djokovic turned the fifth set around, and in four sets last year when Nadal seemingly coped better with the heat in the final.
This year's French Open is another opportunity for Djokovic to join Nadal and Roger Federer in completing the career grand slam.