US Open Tennis 2013 Results: Key Takeaways from Day 9's Matches

Day 9 of the 2013 U.S. Open was an exciting one with some great matches, but there are some very important things to take away from Tuesday's action.

Top seeds Novak Djokovic and Andy Murray advanced, while Tomas Berdych fell victim to an upset at the hands of Stanislas Wawrinka.

On the women's side, Serena Williams advanced without dropping a game, but both Victoria Azarenka and Li Na had to sweat it out in their matches.

Let's take a look at the results and biggest takeaways from Day 9.

Day 9 Results

Winner	Loser	Score
No. 1 Serena Williams	Carla Suarez Navarro	6-0, 6-0
No. 2 Victoria Azarenka	No. 13 Ana Ivanovic	4-6, 6-3, 6-4
No. 5 Li Na	Ekaterina Makarova	6-4, 6-7(5), 6-2
No. 1 Novak Djokovic	Marcel Granollers	6-3, 6-0, 6-0
No. 3 Andy Murray	Denis Istomin	6-7(5), 6-1, 6-4, 6-4
Stanislas Wawrinka	No. 5 Tomas Berdych	3-6, 6-1, 7-6, 6-2

Serena Williams Is in Top Form

In case you needed another indication that Williams is on track to win another Grand Slam tourney, you need not look any further than her performance Tuesday against Carla Suarez Navarro of Spain.

Williams cruised to a 6-0, 6-0 win over the Spaniard in what was her easiest match of the tournament. It's abundantly clear the American is getting stronger as this tourney goes on, and that's bad news for the rest of the women remaining.

Li Na will be Williams' next opponent in the semifinals. Williams emerged victorious in their three previous matches—all on hard courts. In fact, Williams has only lost one match against Na on a hard surface in her career, which came back in 2008.

Victoria Azarenka is on Upset Watch

Azarenka was one of the favorites to win this year's U.S. Open, but after her match with Ana Ivanovic, that thought is fading quickly.

It took everything Azarenka had to top Ivanovic in three sets. Her 21 winners were almost doubled by the Serbian, and she allowed Ivanovic 13 break points, but she had just enough to advance.

Adding to her troubles is the fact that she has just 24 hours to prepare for her next opponent, Daniela Hantuchova, thanks to bad weather. That quick turnaround could do more to derail Azarenka's bid to advance than help it.

These two have split their four meetings in the past, so Azarenka is no stranger to losing to Hantuchova. And with the way she's playing, Azarenka is primed to be upset on Wednesday.

Novak Djokovic is Playing His Best Tennis

After his fourth-round beatdown of Spaniard Marcel Granollers, Djoker appears to be playing his best tennis of the tournament at the moment.

Djokovic has yet to drop a set at Arthur Ashe Stadium in 2013, but his previous opponents at least put up somewhat of a better fight than Granollers. Granted, Granollers stood no chance, but Djokovic didn't waste any time taking care of his inferior opponent, and he did so in an impressive fashion after losing three games in the first set.

By comparison, fellow favorites Rafael Nadal and Andy Murray each dropped the first set in their respective fourth-round matches.

Djoker didn't miss a beat Tuesday, and he has a full head of steam as he inches closer to the U.S. Open final.

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