#2 Andy Murray and his fangs could only sink into nine games in his loss. Photo via d.yimg.com

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The other Andy was sent home Tuesday in the only major shake up on a day that featured tennis of varying degrees of quality.  A highly anticipated semifinal on the women's side was realized, while several intriguing possibilities for later round matches on the men's side were erased.

A rundown of Day 9's six singles matches:

Women's Bottom Half Quarterfinals:

Serena Williams USA (2) def. Flavia Pennetta ITA (10) 6-4, 6-3 -- There have been many grand slam tournaments in which Serena Williams started out playing pretty scratchy tennis only to find her A-Game seemingly out of nowhere in the second week.  This hasn't been one of those tournaments.  Except for some spotty play in her very first set of the tournament vs. Alexa Glatch, Serena has played near her best stuff the entire tournament.  It's been pretty scary to witness.  Flavia Pennetta played near her best tennis in this match, and barely managed seven games against an unstoppable looking Serena, who not only was hitting the ball as hard as ever, but also hit fewer errors than winners, a rare achievement for a women's player as aggressive as she is.  For my money the four most impressive players in this tournament have been Serena, Flavia, Clijsters and Oudin, so it's a shame Pennetta had to run into the buzzsaw that is Serena even this soon.  If she had been alive in the top half of the draw, Pennetta would be the massive favorite to make the final, and almost certainly would have with how well she had played.  Then again, a bunch of players could have potentially done big things in a part of the draw that now features a Bondarenko vs. Wickmayer quarterfinal.

Kim Clijsters BEL def. Li Na CHN (18) 6-2, 6-4 -- When asked in her pre-match interview with Pam Shriver what her strategy was against Clijsters, Li said that she "wasn't going to think, she was just going to go out there and play."  She held true to her promise, playing some of the most brainless tennis imagineable to hand Clijsters a fairly easy win in her first Grand Slam quarterfinal in over two years.  Both Li and Clijsters seemed unaware of each other's nerves throughout, going for too much when simply keeping the ball in play was enough to win most points.  Li and Clijsters each hit nine winners, but made 41 and 25 unforced errors respectively.  Not pretty stuff.  Clijsters didn't need to play well against Li, but she will need to be much, much better if she wants to threaten Serena in the semifinal.  That semifinal will be an unprecedented battle between two players who are each riding twelve-match win streaks at the US Open, and should be framed as an incredibly star-studded de facto final.

Men's Bottom Half Fourth Round:

Marin Cilic CRO (16) def. Andy Murray GBR (2) 7-5, 6-2, 6-2 -- As big a shock as Andy Roddick crashing out in the third round was, Andy Murray being sent home in the fourth round by a less tricky opponent is several times more surprising.  Murray played absurdly lethargic, passive tennis throughout the match, managing only thirteen winners over the three sets, only one more than the twelve Dinara Safina scraped together in her three-set third round exit.  Cilic wasn't playing incredible defense, either--Murray simply wasn't forcing the issue.  Counter-punching is a fine mindset to have, but at some point if you're getting knocked down over and over you had better start throwing some punches of your own before you get KO'ed.  Murray never seemed to realize that, and paid the price dearly, winning only nine games on his way out of the tournament.  It's a huge win for Cilic, to be certain, and puts him into his first grand slam quarterfinal.  He did not play exceptionally against Murray, but he did an admirable job of keeping his foot on the gas and not letting Murray make things interesting in the last two sets despite a few close service games.  Cilic shouldn't be able to do much against del Potro, but this win should be a big enough takeaway from this tournament to give the big Croat a lot of confidence going into the indoor season.

Juan Martin del Potro ARG (6) def. Juan Carlos Ferrero ESP (24) 6-3, 6-3, 6-3 -- What could have been a nice match-up between power and speed turned into a not-so-nice rout by power of powerless.  del Potro smacked 22 aces and was never broken by Ferrero, who was simply outgunned in every category and left without any answers.  del Potro had been slated to face Murray in the quarterfinals for what would have been a match-up of their close final in Montreal, but instead faces Cilic in what should be a far more straightforward challenge for him.  Except for that one set he dropped to the flashy Daniel Koellerer, del Potro has been the most solid of the four bottom-half quarterfinalists.  Getting ahead of ourselves, his potential semifinal against Nadal has potential to be a classic.

Rafael Nadal ESP (3) def. Gael Monfils FRA (13) 6-7(3), 6-3, 6-1, 6-3 -- I had high expectations for brilliance in this match, and my wishes were met for the first set and a half or so.  Monfils, always at his best in front of a huge crowd, put together some incredibly flashy rallies with Nadal, the two chasing down apparent winners again and again to give the crowd their money's worth early.  Running down every Nadal shot quickly took its toll on Monfils about an hour and a half into the match, as he clearly looked out of gas by the midway point of the second set.  The third and fourth sets featured some flashes of brilliance, but were fairly routine for Nadal in the end.  While the back end didn't live up to the front of the match, the beginning was so electrifying that it's tough to be disappointed.  Nadal's fitness looked 100%, showing no signs of the abdominal or knee injuries that have floated around him recently.  While other players possibly exhausted by the end of the fortnight, the time Nadal missed this summer could wind up being a blessing, giving him the rest he needed to have energy enough to play fresh tennis into the final weekend.

Fernando Gonzalez CHI (11) def. Jo-Wilfried Tsonga FRA (7) 3-6, 6-3, 7-6(3), 6-4 -- The offense in this match was incredible, with both players using their powerful forehands to end points as quickly as possible.  Neither had any answer for the other's power, so they wound up getting in each other's way very little, hitting  fairly unimpeded winners constantly.  In fact, this was the only match of the day in which both players were in positive territory for their winners to unforced errors ratio.  Gonzalez got off to a rough start as he smashed a racquet once falling down 1-4 in the first, but from then on he was the slightly more solid of the two the rest of the way.  Though the match often roared, it unfortunately went out with a whimper, as Tsonga double faulted twice in the final game to gift Gonzalez the deciding break.  Gonzalez faces Nadal in the next round, a match he shouldn't have much of a shot in given the pair's recent head to head.  But he's already lived past his seeding, and made the quarterfinals of the US Open for the first time since 2002, which is certainly an accomplishment to be proud of.