Day 9 of the US Open is on the slate and the days left at Flushing Meadows are numbered.
However, there is still tons of exciting tennis left to be played at the Open, with the best in the business beginning to match up with the rest of the elite. With very few matches left to be played at the tournament, each contest offers loads of excitement.
On Tuesday, Rafael Nadal, Andy Murray, Vera Zvonareva and Andy Roddick are all in action. Most of the players left in both the men's and women's tournament can make a legitimate case for having a chance to triumph at the Open.
Here are five things to keep an eye out for on Day 9 of the US Open.
Coming into the 2011 US Open, both Donald Young and Angelique Kerber shared the fact that they'd only ever made it to the third round at a Grand Slam.
On Tuesday, Young and Kerber are both looking to improve their best result. Young is coming off back-to-back wins over No. 14 Stanislas Wawrinka and No. 24 Juan Ignacio Chela. His next opponent is No. 4 Andy Murray as Young looks to beat the last seeded "four" at the Open and advance to the quarterfinals.
In the only meeting between the two players earlier this year, Young stunned Murray in straight sets. However, Murray was not confident at the time and has come a long way since the loss. Also, Young's serve will be a liability against Murray, who is a fantastic returner.
Kerber recorded her biggest win in the second round when she topped No. 12 Agnieszka Radwanska. She is set to play No. 26 Flavia Pennetta for a spot in the semifinals. Kerber has had the benefit of a great draw, but has still taken care of business in each match.
My Prediction: Young's serve will cost him, as he loses to Murray in four sets. Kerber is stopped in her tracks by Pennetta, who controls the match from the onset.
Rafael Nadal understands just how good Gilles Muller is.
He's 2-1 against the Luxembourg native, but has never faced him on a hard court. Nadal has seen Muller in Wimbledon twice in his career, with Muller taking one of the two contests. However, that was in 2005 and Nadal won the most recent match between the two a few months ago.
Muller's most impressive win thus far was a comeback four-set victory over Ernests Gulbis. I had predicted that Gulbis would break through at this tournament, and after he manhandled No. 16 Mikhail Youzhny in straight sets, I feel strongly that I was right.
My Prediction: Nadal will have his hands full, but will win in either three or four sets after taking the first in a breaker.
Andy Roddick is coming into this year's US Open with a different aura around him then ever before.
For every year that I can remember, there was a solid group of people that thought this would be Roddick's year to grab his second US Open. This year, Roddick is the No. 21 seed and there's little hype around his chances to go all the way in New York.
Roddick's got the job done thus far, but he's been lined up against inferior players. His opponent in the Round of 16 is David Ferrer, the No. 5 player in the world. Ferrer is playing a much more aggressive game than in year's past and he's been incredibly consistent all season.
Can Roddick win this match? Yes, but not playing the way he has in the first three rounds. He needs to inch closer to the baseline and be more aggressive. If he tries to play defensively against Ferrer, the Spaniard will make him pay.
My Prediction: Roddick has shown time and time again that he is extremely reluctant to step up and hit the ball flat. Ferrer will move him around all night, earning the win in four long sets.
Sam Stosur is the woman who's impressed me the most at the 2011 US Open.
Stosur has won back-to-back three-set thrillers, showing how determined she is to win a major championship. A three-and-a-half-hour marathon win over No. 24 Nadia Petrova was followed with a two-and-a-half-hour showdown with Maria Kirilenko.
Stosur has seen the momentum swing against her on multiple occasions, but refuses to bow out of the Open. Now, Stosur is faced with world No. 2 Vera Zvonareva in the quarterfinals. Zvonareva has played significantly less tennis than the Australian, but is not used to the pressure points quite like Stosur is.
My Prediction: Stosur fights the whole way, but runs out of gas and magic in a three-set loss.
John Isner has been thorough in asserting his powerful serve at the 2011 US Open.
Isner has only been broken two times at Flushing Meadows, with both coming in his first-round match against Marcos Baghdatis. In his last two rounds, Isner has only faced 10 break points, saving all of them.
Isner's next opponent is No. 12 Gilles Simon, who is coming off a huge win over Juan Martin del Potro in the third round. Isner will have to do more than just serve against the Frenchman, who will not be broken as easily as Isner's previous counterparts.
Isner has impressed me the most of any men's player, but it's due in part to the fact that I had extremely low expectations of the American coming into the tournament.
My Prediction: Isner plays solid tennis throughout, but conditioning fails him as he loses in five sets.