The return of the real Rafa?

The tennis season is divvied up into finite chunks. There's the Australian summer, the Indian Wells and Miami double in the U.S., and now the European clay swing.

This part of the year is, of course, when Rafael Nadal especially thrives. But his knees are a concern as he tries to fend off Novak Djokovic and Roger Federer.

The streak now over, and the pressure thus off, Victoria Azarenka seeks to win a second consecutive major -- this time on her least productive surface.

Here are five burning questions with the European dirt tournaments kicking off this week with the women in Barcelona and next week in Monte Carlo with Rafa, Nole and other leading men.

What should we expect from Nadal?

The lone blotch on Nadal's clay-court résumé came in 2009. A knee injury bothered him; he was deeply affected by problems between his parents; and he confronted an inspired opponent at the French Open (get well soon, Robin Soderling).

Heading into next week, his left knee is a question mark. With Nadal having spent the entire month of February away from the tour, it wasn't a good sign that his woes returned. How will the knee then react after Monte Carlo, at Nadal's beloved Barcelona, Madrid, Rome and Roland Garros?

His condition likely was one of the reasons he looked annoyed and grumpy in Indian Wells and Miami, but he also was troubled by another off-court matter: The changes he wants made to the game, such as a two-year ranking system, are going nowhere, and he was fed up enough to step down from the player council.

Thankfully for Nadal, he says the knee isn't as bad as it was three years ago, when he was forced to skip Wimbledon as the defending champion, and issues stemming from his involvement with the council pale in comparison with the sadness he felt when his mom and dad were going through a separation.

He is still the man to beat.

How important is Monte Carlo?

The first tournament of a nearly two-month clay stretch wouldn't figure to be vitally important. However, if Djokovic can do to Nadal in Monte Carlo what he did in Rome and Madrid last year, it's sure to have a knock-on effect.

Djokovic's win in Madrid affected Nadal to such an extent that he almost lost to an Italian wild card in his next outing. Clearly lower than usual on confidence, Nadal then labored to the French Open title. It began with a five-set win over John Isner, and matches he usually would win in three easy sets turned into something much more difficult. If ever there was a time for Federer to down Nadal at the French -- about the only thing outside the Davis Cup and Olympics he hasn't done -- that was it in the final.

But here's what Djokovic is up against in Monte Carlo, where conditions resemble the French: Nadal is the seven-time defending champion and, in his past five visits, has dropped a mere two sets (Djokovic, Murray).

If Nadal upends Djokovic in the final after a narrow loss to the Serb in Melbourne, perhaps he'll think he has turned the corner. Imagine his confidence then.

Can Serena win in Paris?

Serena Williams made a return to clay after a two-year absence and romped to the title in Charleston this past weekend. It was green clay, not red, and the surface was slightly faster, but it was dirt, nonetheless. For a player whose on-court etiquette has been criticized, and rightfully so, Williams also showed class by genuinely consoling Sabine Lisicki when the German retired in the quarterfinals.

Williams told reporters she loves playing on clay. Was it because of the sliding or the ability to construct points? Nah. Her reply was humorous and probably honest.

"I don't have to go crazy and move my feet so much," she said.

An ankle injury meant Williams wasn't 100 percent at the Australian Open, and she needs to be healthy to make a deep run in Paris. She is now. At 30, she's not too old to win, is in great shape and has a serve that remains the best in women's tennis, and an upset loss in Melbourne to Ekaterina Makarova serves as motivation.

Williams, as it stands now, is one of four leading contenders at Roland Garros. The others: Petra Kvitova, Samantha Stosur and Azarenka.

Who is the top U.S. men's hope?

The last U.S. man to reach the quarterfinals at the French Open was Andre Agassi in 2003. Extending Nadal to five sets in 2011 and beating Federer and Jo-Wilfried Tsonga on clay this season in the Davis Cup suggests Isner can end the drought. He's maturing from the baseline; the serve is still huge; and he has time to line up his shots on clay.

By now, we know Isner can beat just about anyone; he added Djokovic to the list in slow Indian Wells. But Isner has to maintain that level against lesser foes and down the players he should in the first week of a Grand Slam event without expending too much energy. He'll be pumped playing in Monte Carlo next week after ousting Tsonga at the same venue on Sunday.

The first priority for Andy Roddick, meanwhile, is to avoid injuries and illness and work his way back into match shape in time for Wimbledon.

Will there be another first-time women's winner at the French?

After Azarenka, the hottest player on the women's tour is Agnieszka Radwanska at 26-4. Radwanska won the biggest tournament of her career in Miami, so she will be filled with confidence making the transition to clay. Unfortunately for the Pole, though, clay isn't her preferred surface.

For the first time in a while at a Slam, Caroline Wozniacki won't be the No. 1 seed. That's a good thing, as expectations will be diminished. Wozniacki has plenty of points to defend before Roland Garros, so, before looking up, she should make sure she doesn't slip lower than her current No. 6 in the rankings. As for France's Marion Bartoli, one suspects her semifinal showing last year will be her high-water mark at her home major.

If there's one player to look out for, it could be Julia Goerges. Goerges sizzled on clay in 2011 and already has made progress in her overall game this season.

However, odds are that the streak of first-time Slam winners, which is at four, will end in early June.