Melanie Oudin (born September 23, 1991) is a former American tennis player and former world junior No. 2. She was a member of the American Fed Cup team from 2009 to 2011 and winner of the 2011 US Open mixed doubles title, with fellow American player Jack Sock. As a 17-year-old in the middle of 2009, Oudin reached the round of 16 of the Wimbledon Championships, followed by a quarterfinal at the US Open six weeks later. She reached a career-high ranking of world No. 31 on April 19, 2010.

Oudin turned professional in February 2008. In April 2008, she received a wildcard at the WTA tournament in Miami where she lost in the first round to Tathiana Garbin in three sets. In August, Oudin received a wildcard into her first Grand Slam main draw at the US Open. She was defeated by Australian Jessica Moore 7-6, 7-6.  In October that year, Oudin participated in the Bell Challenge in Quebec City. In the first round, she defeated third seed Sybille Bammer, 6-4, 3-6, 7-5. In the second round, she defeated Russian Olga Puchkova, 6-1, 7-6. Reaching her first WTA quarterfinals, she was defeated by sixth seed Bethanie Mattek, 7-6, 6-1.  Oudin began 2009 by qualifying for the main draw of the Australian Open. She was then defeated in the first round by Akgul Amanmuradova, 6-1, 6-4.  At the 2009 Wimbledon Championships, Oudin entered as a qualifier. She defeated No. 29 Sybille Bammer in three sets in the first round and Yaroslava Shvedova in three sets in the second. Oudin defeated also world No. 6 Jelena Jankovic, 6-7, 7-5, 6-2 but lost to Agnieszka Radwanska in the fourth round, 4-6, 5-7.  At the US Open, Oudin entered as a wildcard. In her first-round match, she easily defeated Anastasia Pavlyuchenkova, 6-1, 6-2. In the second round, she stunned fourth-seeded Elena Dementieva, 5-7, 6-4, 6-3, in her Arthur Ashe Stadium debut. Then in the third round, she defeated a resurgent Maria Sharapova, 3-6, 6-4, 7-5. At 17 years of age, Oudin reached the fourth round of a major event for the second consecutive time. In the fourth round, she played another Russian, 13th-seeded Nadia Petrova. She defeated Petrova, 1-6, 7-6, 6-3, to reach the quarterfinals of the event. She became the youngest woman since Serena Williams in 1999 to reach the quarterfinals at the US Open, and the youngest since Maria Sharapova to reach the quarterfinals at a Major. Her Cinderella story ended when ninth-seeded Caroline Wozniacki defeated her, 6-2, 6-2. A standing ovation occurred when Oudin was leaving the court. After the US Open, Oudin's ranking rose into the top 50, her first appearance there.

Using a quote from the above article, answer the following question: What rank did she end up with?
After the US Open, Oudin's ranking rose into the top 50, her first appearance there.