Passing shots: Five storylines to watch at the French Open, more

1. Can Ana Ivanovic mount a serious title defense?

It's been a dicey 52 weeks since Ivanovic reached the summit of the WTA rankings with her victory in last year's French Open.

The 21-year-old Serb injured her thumb shortly after her Paris victory, lost in the third round at Wimbledon and ceded the No. 1 ranking after 12 weeks on top. She failed to win back-to-back matches in her next five events, including the U.S. Open.

Shortly after her third-round defeat at this year's Australian Open, her ranking dropped to No. 8. Following an ignominious exit at last month's Italian Open -- she squandered a 4-0 lead in the third set in a 6-1, 3-6, 6-4 loss to Agnieszka Radwanska -- Ivanovic withdrew from last week's Madrid event to ensure her health for Roland Garros.

A strong performance in Paris could subvert the one-Slam wonder murmurs. But will her fitness comply?

2. Can anybody beat Rafael Nadal in Paris?

The knee-jerk response is yes. Didn't Roger Federer just demonstrate his clay-court mettle in Nadal's backyard and announce his candidacy for the French, the lone Grand Slam missing from his otherwise impeccable résumé?

Not so fast.

Nadal's next loss at Roland Garros will be his first. The four-time French Open champion is 28-0 dating to his 2005 debut, when he derailed Federer's bid for a career Slam in the semifinals and became the first teenager to win a Major since Pete Sampras at the 1990 U.S. Open.

There's also the issue of the surface on which Federer beat Nadal last Sunday: Many players, including Nadal, claimed the clay at La Caja Mágica played more like a hard court, due in part to the altitude of the venue.

One could also argue that Federer might not have beaten Nadal if Novak Djokovic hadn't first softened the Spaniard in the previous day's epic four-hour semifinal clash -- an early candidate for Match of the Year -- in which Nadal saved three match points before advancing in an extended third-set tiebreak.

It would be unfair to stamp an asterisk on Federer's victory, and there's certainly no overstating the psychological benefits of shaking his eight-month title drought before the French. But if there's anybody Nadal might be relieved to see on the opposite side of the draw, the guess here is that it's Djokovic and not Federer.

3. Can Dinara Safina silence the doubters once and for all?

When the 23-year-old Russian inherited the No. 1 ranking from Serena Williams earlier this month, it was hardly a peaceful transfer of power. "We all know who the real No. 1 is," Williams said after slipping to No. 2.

Safina, to her credit, took the high road and let her performance do the talking.

Until Friday.

"I guess they're jealous that I'm so young and No. 1," Safina told reporters in Madrid after defeating Patty Schnyder in the semifinals, one day before whipping Danish teenager Caroline Wozniacki in straight sets for the title.

"To become No. 1, it's not just winning the Grand Slams, it's how you compete the whole year," Safina said. And she's right. Safina, who's reached the finals in 12 of her past 20 events, has earned the ranking on the merit of her week-to-week consistency.

While Serena has suffered a pair of puzzling opening-round exits since her swipe, the real No. 1 -- no quotation marks necessary -- has won 10 straight matches and collected titles in Rome and Madrid.

Her Friday comments aside, Safina has handled the pressure of justifying her No. 1 ranking with poise. But earning her Grand Slam stripes with a victory at Roland Garros -- where she made her breakthrough in 2008 with a run to the final -- would alleviate the burden of proof.

4. How will Maria Sharapova's shoulder hold up?

It's been a long way down for Sharapova, whose ranking has plummeted to No. 126 during her nine-month absence from singles after shoulder surgery.

The 22-year-old Russian played her first singles match since August at the Warsaw Open on Monday, earning a hard-fought, three-set victory over Italy's Tathiana Garbin in the first round. The rust showed. Playing with a criss-crossed bandage on her right shoulder, Sharapova required nine match points to finish her 68th-ranked opponent.

Sharapova has always weathered her share of criticism. But the three-time major champion has spent 17 weeks atop the WTA rankings -- six more than Venus Williams -- and could become the 10th woman to achieve a career Grand Slam with a victory at Roland Garros.

Without a dominant No. 1 player on the women's side (five different players held the top ranking in 2008), can Sharapova capitalize on the opportunity and make a deep run in Paris?

5. Can any American man survive until the second week?

Of the three Americans in the ATP top 50 -- Andy Roddick, James Blake and Mardy Fish -- none has advanced to the Round of 16 at Roland Garros.

It's been a decade since Andre Agassi lifted the Coupe des Mousquetaires and 18 years since Jim Courier's back-to-back Paris triumphs. But Americans have come up empty in the years since.

The point-prolonging clay of Roland Garros neutralizes the sort of aggressive, attacking approach typically favored by players from the United States. But Americans have shown signs of life during this clay-court season, with Roddick offering Federer a spirited three-set challenge in the Madrid quarterfinals and Blake holding match points before losing to Albert Montanes in the Estoril Open final.

While Federer and Nadal toiled in Madrid, Wimbledon showcased its new retractable roof on Centre Court with an entertaining slate of exhibition matches.

Agassi and Steffi Graf, the married couple with eight Wimbledon singles titles between them, played a good-natured mixed doubles exhibition with Tim Henman and Kim Clijsters before the men and women paired off in best-of-one singles matches.

More than 15,000 spectators, including former and current stars like Boris Becker and Andy Murray,peered upward as the 10 trusses supporting the translucent roof covered the court.

It didn't take long for the expensive renovation to get justification: Rain started falling over the All England Club shortly after the the roof closed for the start of the doubles match, which Henman and Clijsters won 7-6 (6). Agassi defeated Henman 6-4 in the men's singles match, and Clijsters downed Graf by the same score.

Agassi and Graf aren't the only former superstars climbing back into the saddle. Pete Sampras is taking part in the "Millennium Challenge" on July 27.

Sampras, whose record of 14 Grand Slam titles is under threat from Federer, is scheduled to face Marat Safin in a rematch of the 2000 U.S. Open final on opening night of the 83rd annual L.A. Tennis Open.

Safin won the first of his two Grand Slam crowns against Sampras at Flushing Meadows in 2000 and holds a 4-3 edge in their all-time series.