Kei Nishikori makes history and Ekaterina Makarova cruises on Day 10

NEW YORK -- Day 10 of the U.S. Open saw two upsets, with Ekaterina Makarova getting the best of Victoria Azarenka, and Kei Nishikori making history. 

​What happened

Kei Nishikori recovers, beats No. 4 Stan Wawrinka, and makes history: The No. 10 seed became the first Japanese man since 1918 to advance to the semifinals of a Slam when he recovered from his 2:26 a.m. finish just 36 hours ago on Tuesday night to beat Wawrinka 3-6, 7-5, 7-6 (7), 6-7 (5), 6-4 in more than four hours on court. Nishikori has had the reputation of being physically fragile, too humble in his ambition, and -- this a curse word in sports -- too soft to fight through tough matches.

U.S. Open by the Numbers

23,771

Erick W. Rasco/Sports Illustrated

The number of seats in Arthur Ashe Stadium, the largest tennis stadium in the world. In 1997, the venue, which also has 90 luxury suites, five restaurants and a two-level players’ lounge, replaced Louis Armstrong stadium as the primary court at the Open. A $100 million retractable roof will be completed over the stadium by the end of 2017.

51

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Number of concession stands at the U.S. Open. In 2013, 225,000 hamburgers and hot dogs, and 7.5 tons of crab, shrimp and lobster were served. In addition 18,000 pounds of unused food was donated to the community

180,000

Erick W. Rasco/Sports Illustrated

Number of feet of string (about 34 miles) that will be used during the 2014 Open. Wilson will string approximately 4,500 racquets for the tournament and on its busiest day, will string between 400 and 450.

70,000

Erick W. Rasco/Sports Illustrated

Number of tennis balls used at the U.S. Open.

1,428

Erick W. Rasco/Sports Illustrated

Number of credentialed media that covered the 2013 U.S. Open, representing 42 countries. The tournament was broadcast to 200 nations.

721,059

Erick W. Rasco/Sports Illustrated

Number of fans who attended the 2009 U.S. Open, an alltime tournament record. The 2013 tournament was represented by a fan from each of the 50 states.

70

Erick W. Rasco/Sports Illustrated

Number of matches won in Arthur Ashe Stadium by Serena Williams through the 2014 round of 16, the most by any player since the stadium’s inaugural year in 1997. Williams is competing for her third consecutive Open title, sixth overall, and her 18th Grand Slam win.

262

Ball persons used at the 2013 U.S. Open out of 400 people who tried out.

Yet there he was, managing his emotions and his energy levels, taking Wawrinka to five sets and it was the Australian Open champion who blinked. Serving at 4-5 in the final set, Wawrinka fell behind 15-40 and finally lost the match when he put in a nervous second serve before hitting an even more nervous forehand that let Nishikori take control of the point for the win. The win will put Nishikori back into the top ten and he will play either Novak Djokovic or Andy Murray in the semifinals. But first, rest. With the men's semifinals being played on Saturday, Nishikori will have two days to recover from over eight hours of tennis in the last 48 hours. 

Novak Djokovic fends off Andy Murray to advance to the semifinals: The No. 1 seed took more than three hours into the early morning on Thursday to take down No. 8 seed Murray. You can find an in-depth look and analysis on the match here.

No. 1 seed Djokovic fights off Murray for a spot in the semifinals

​​Ekaterina Makarova handles Victoria Azarenka to make her first Slam semifinal: The 17th seed never blinked and never wavered, as she coolly dispatched of two-time defending finalist Azarenka 6-4, 6-2 to advance to the semifinals. The 26-year-old from Russia -- and Steffi Graf doppelganger -- has not lost a set heading into the semifinals, after beating Eugenie Bouchard in the fourth round in straight sets as well. Shy and good-humored, Makarova is letting her tennis do the talking. She's also in the women's doubles semifinal after she and partner Elena Vesnina beat Serena and Venus Williams on Tuesday. 

Mailbag: 6 thoughts on the USTA, quarterfinals and more

The win means there will be no U.S. Open final rematch between Serena Williams and Azarenka in the semifinals, which may be for the best. Azarenka, understandably, was nowhere near her the top of her game this tournament, needing three sets to get past Misaki Doi in the first round and No. 145 Aleksandra Krunic in the fourth round. After the loss on Wednesday, Azarenka's PR manager told reporters she had been suffering from food poisoning and did not practice on Tuesday. Azarenka confirmed she was ill but refused to talk about it any further. But context is context, and this was a great tournament for her. To make the quarterfinals without playing to her potential leaves her in good stead for the rest of the season. She'll likely fall outside the top 20 to No. 24 after this tournament, but has little to defend for the rest of the season. Her charge up the rankings should be fun to watch. 

Serena Williams advances to the semifinals: After a slow start, Williams won six straight games and rolled to a 6-3, 6-2 win over Flavia Pennetta. She still has yet to come close to losing set this tournament. 

Photo of the day

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Video of the day

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Quote of the day

Azarenka after her loss to Makarova: "How do you think somebody will answer a question like that? Of course it is disappointing. It's not about that you have been two times in the final before that's going to make it better. It just is what it is today. It's not the end of the world. It's something I can take positive from this tournament, you know. Two months ago I didn't even think that I was going to be able to play today. But, you know, trying to ask and put some kind of pressure like that with those questions I think is no point."

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