Report Card: Rafael Nadal now a favorite to win the U.S. Open?

Save for his premature Wimbledon loss, Rafael Nadal has been dominant since his return to the ATP Tour in February. (Aaron Doster/Icon SMI)

MASON, Ohio -- The Report Card hands out grades for the week in tennis. Last week, Rafael Nadal and Victoria Azarenka cemented their hard court bona fides with titles at the Western & Southern Open in Cincinnati, while John Isner rained on the drought of U.S. men in the ATP rankings.

Rafael Nadal: A. The stats surrounding Nadal's 2013 season are just astounding. In the 12 tournaments he's played, he's made the finals in 11 of them and won nine titles. He's now jumped to No. 2 in the rankings, passing Andy Murray, who happens to be the reigning champion at two Slams (side note: where's all the outrage about rankings system now?). Did anyone really think this was possible when Nadal made his comeback in Vina del Mar, Chile, in February? To recap: he played some sloppy tennis at the tiny clay court event and still advanced to the final, but lost to No. 73 Horacio Zeballos.

As Nadal continues his tear and shows no ill-effects physically, one could argue that he's the favorite going into the U.S. Open and could overtake Novak Djokovic for the No. 1 spot. Novak Djokovic hasn't won a title since Monte Carlo, Murray heads into the tournament with little match play, Roger Federer is as vulnerable as ever and Juan Martin del Potro and Tomas Berdych can be unreliable at the big tournaments.

For those who enjoy a little bit of foreshadowing, consider this: The last man to complete the Canada-Cincinnati double went on to win the U.S. Open. That man was Andy Roddick in 2003.

Victoria Azarenka: A. After beating Serena Williams 2-6, 6-2, 7-6 (6) to capture her third title of the season, Azarenka said her experience and maturity has taught her how to "win ugly". That's precisely how I'd describe her title run in Cincinnati. She was great at times (her win over Caroline Wozniacki in the quarterfinals was a good one), and virtually unwatchable at times (her semifinal against Jelena Jankovic featured 23 breaks of serve in 27 games). However, Azarenka was at her competitive best against Williams, summoning some of her best tennis in the third-set tiebreaker, where she played a game-changing volley perfectly to set up her win.

"At this level, at this moment, you have to come up with something extraordinary if you want to win," she said after the match. "Just to sit and wait and hope for a mistake, forget about it. I learned that last couple of meetings that is not going to happen. So I was just trying to make make my chances, make my opportunities happen, and I knew I had to step up and be aggressive. Yeah, that volley was pretty good. Should come more to the net."

John Isner: A-plus. Isner opened the week fielding questions about the fact that no American men were ranked inside the top 20 for the first time since the ATP rankings were introduced 40 years ago. That drought was short-lived. He beat No. 1-ranked Djokovic to make his second ATP Masters 1000 final, and he's soared back up to No. 14 in the rankings. Isner insisted he never thought of himself as the savior of American men's tennis, but he's the only guy from the U.S. who can consistently trouble the top players and contend for big titles.

Marion Bartoli: A-plus. Marching to the beat of her own drummer, Bartoli shocked everyone when she decided to hang up her racket after a quiet loss to Simona Halep in her first match in Cincinnati. "Who in the world retires in Mason, Ohio?" was a question that came up often throughout the week, but Bartoli wasn't too concerned about that. Questions will continue to swirl as to whether the decision was rash and whether she'll mount a comeback sooner rather than later (her name remains on the WTA rankings and she'll reportedly continue to be subject to WADA protocols, meaning she could return to competition anytime) but Bartoli got to walk away at the top of her game and on her own terms. How can anyone fault her for that?

Caroline Wozniacki: B-plus. Wozniacki showed some positive play this week. She came back from a break down against Petra Kvitova to win a key match  3-6, 6-2, 6-3, and pushing Azarenka as well, losing 6-3, 7-6 (5) in the quarterfinals. She was aggressive in both those matches, returning well and going for winners on balls when we're used to her just pushing back. If she can continue that style of play through the U.S. Open, a turnaround is just around the corner.

Serena Williams: B. She didn't play her best tennis in Cincinnati, but still, she came within points of winning her third-straight title since Wimbledon. She's still the favorite to win the U.S. Open, but consider this: Serena is 8-2 in finals this year. Those two losses? They came to Azarenka on hard courts.

Roger Federer: B. He played his best match in almost a year against Nadal in the quarterfinals, only to lose 5-7, 6-4, 6-3. With that, Federer falls to No. 7 in the rankings, his lowest ranking since October 2002. Here's what the top 10 looked like that week: 1. Lleyton Hewitt, 2. Andre Agassi, 3. Tommy Haas, 4. Marat Safin, 5. Tim Henman, 6. Juan Carlos Ferrero, 7. Federer, 8. Sebastien Grosjean, 9. Jiri Novak, 10. Albert Costa.

Li Na: B-minus. How's this for letting someone off the hook: In her semifinal against Serena, Li had set point on her own serve and double-faulted. A few games later, when Serena had break point to win the set, Li double-faulted to hand it to her. Then on match point, Li, you guessed it, double-faulted. Three key points in the match and Serena didn't even have to swing her racket.

Novak Djokovic: B-minus. The best player on hard courts and No. 1 player in the world hasn't won a hard court tournament since Dubai in February, and he hasn't made the final of a hard court ATP Masters 1000 this year. After his 7-6 (5), 3-6, 7-5 loss to Isner in the quarterfinals, he was understandably terse. It's yet another tight match in which he's come out on the losing side this year, unable to play his best tennis in the most important moments.

"I just played a very bad match overall," he said. "Terrible match. From beginning to end, except the start of the second set, I was just a different player totally." Can he pull it together in time for the U..S. Open?

Andy Murray B-minus. It's easy to forget that Murray even played the tournament. His quarterfinal loss to Tomas Berdych wasn't necessarily a bad one -- Berdych played extremely well to earn a 6-3, 6-4 victory. But Murray will go into the U.S. Open with only five matches under his belt since his Wimbledon victory. Then again, he went into the Open last year with just three matches on hard courts and walked away as the champion.

Maria Sharapova: C. Losing in her opening match to Sloane Stephens wasn't a horrible loss given that it was the Russian's first match since Wimbledon. But she'll now go into the U.S. Open with just one match on hard courts and without a coach, after immediately firing Jimmy Connors after the loss. That partnership had question marks all over it the minute it was announced so the split itself isn't surprising, but the timing is tough.

Ana Ivanovic: D. Ivanovic looked well on her way to a comfortable win against Alize Cornet in the first round, building a 6-2. 5-2 lead on the Frenchwoman and earned five match points only to lose 2-6, 7-6 (8), 6-4. Demoralizing stuff.

Ryan Harrison: B-plus. Back into the Top 100, Harrison scored his biggest win since January, beating No. 37 Alexandr Dolgopolov 7-6 (3), 6-4 in the first round of Cincinnati. He then played his best match against a top 5 guy, pushing David Ferrer in a 7-6 (5), 3-6, 6-4 loss.

Tomas Berdych: A-minus. Always a dark horse at the U.S. Open, Berdych routined Murray in the quarterfinals and had his chances against Nadal in the semifinals before losing 7-5, 7-6 (4). A semifinalist in New York last year, he proved again in Cincinnati why he's so dangerous on hard courts.

Juan Martin del Potro: B-minus. I don't know what was in the water in Cincinnati, but no double-fault on a key point stood out more than Del Potro's double on match point against Isner in the semifinals. He let Isner off the hook and then unraveled to lose 6-7 (5), 7-6 (9), 6-3.

Jelena Jankovic: B-plus. The Serb never fails to play some of her best tennis in Cincinnati. This year she made the semifinals after beating Sabine Lisicki, Ekaterina Makarova, Sloane Stephens and Roberta Vinci, before losing to Azarenka in a break-fest, 4-6, 6-2, 6-3.

Mackenzie McDonald: A. The 18-year old from California was the story out of qualifying, where he became the youngest unranked player to qualify for an ATP Masters 1000 event. He lost in the first round to David Goffin, but there was a lot to like about McDonald's poise. His decision to forgo turning pro and opt to play in college at UCLA was a smart one. He'll get a lot of matches under his belt, and use the time to become physically stronger.

Dmitry Tursunov: A. The Russian qualifier continued his solid 2013 season with a run to the quarterfinals, the first qualifier to get that far in Cincinnati since 2002. En route, he beat No. 4 David Ferrer 6-4, 6-3.

WTA Coaches: D. Sharapova splits with Connors and Sam Stosur splits with her long-time coach Dave Taylor, both on the eve of the last Slam of the year (Stosur will have Alicia Molik in her corner for the U.S. Open). In addition, there was this unfortunate example of on-court coaching with Lauren Davis. I'm agnostic about on-court coaching generally, but when players call their coaches down and all they get is "Be positive" or "focus", I can't help but wonder what's the point of the whole experiment.

ITF: F. It's been three weeks since news leaked that Marin Cilic failed a doping test in April and there's been not a peep from the ITF on the matter. The ITF's policy of not commenting on the existence or progress of any potential doping violation until a final decision has been made by an independent tribunal is simply untenable in this day and age, where tennis needs more transparency in how it polices doping violations.

WTA television coverage: D.