Li Na. At the Australian Open, she lost to Kurumi Nara in the opening round. She also lost in the second round in the doubles event with Hsieh against Shahar Pe'er and Sílvia Soler Espinosa. Peng then won two consecutive doubles titles, winning the Pattaya Open with Zhang Shuai defeating Alla Kudryavtseva and Anastasia Rodionova in the final, and winning the Qatar Open with Hsieh Su-wei defeating Květa Peschke and Katarina Srebotnik in the final. On 17 February, Peng became the world No. 1 in doubles, making her the first Chinese tennis player (man or woman, in singles or doubles) to reach world No. 1. Peng and Hsieh continued their success by winning three more titles in the season, including two Premiere Mandatory events (Indian Wells and Beijing) and French Open. In the Wimbledon Championships, they failed in defending their title and also lost their No. 1 ranking. However, since Wimbledon, Peng found her pace in the singles events. She reached the last 16 at the Wimbledon Championships. She also clinched title in the 125K event in Nanchang. At the US Open, Peng made her first Grand Slam singles quarterfinal and semifinal appearances, defeating compatriot Zheng Jie, fourth-seeded Agnieszka Radwańska, 28th-seeded Roberta Vinci, 14th-seeded Lucie Šafářová, and rising star Belinda Bencic en route, all in straight sets. In the semi-final, she had to retire against 10th-seeded Caroline Wozniacki in the semifinal at 6–7, 3–4 down, when she suffered severe cramps due to heat illness and had to be taken off court in a wheelchair. She skipped playing the following Hong Kong Open to recover, but made promotional appearances there. She came back to the game in the Wuhan Open, China Open, and Tianjin Open. Peng and Hsieh entered the WTA Finals as the second seed. They beat Garbiñe Muguruza/Carla Suárez Navarro and Alla Kudryavtseva/Anastasia Rodionova in straight sets to reach the final. However, they lost disastrously to Cara Black/Sania Mirza. They pairing then came to conclusion as Peng had previously announced during the US Open. 2015: Injury Peng had a difficult 2015 season. Due to injuries, she had a lot of first round or second round losses. Her best performance of the season was fourth round of the Australian Open, which tied her best performance, although she lost it to second seed and the eventual runner-up Maria Sharapova. Peng failed to win even one doubles match in 2015. She started