In 2015, Serena Williams decided to start her season at the exhibition event in Perth, at the Hopman Cup teaming up with John Isner, losing in the final to the Polish pairing of Agnieszka Radwańska and Jerzy Janowicz. At the Australian Open, Williams claimed her 19th slam defeating Maria Sharapova, putting her 2nd in the most slams won in the Open Era. Williams ended her 14-year boycott of the BNP Paribas Open but withdrew prior to her semifinal match. She then claimed her eighth Miami Open title defeating Carla Suárez Navarro in just 56 minutes in the final after winning a tough three-set semifinal match against Simona Halep. She then reached the final of the French Open and claimed her 20th slam defeating Lucie Šafářová in three sets, making her only the second person to win each slam three times. She backed it up by winning her 6th Wimbledon title against Garbiñe Muguruza to become the first person to win three slams six times and first player since Steffi Graf to win the first three slams of the year. Williams returned from an elbow injury in Toronto but was shocked by Swiss teen Belinda Bencic in the semifinals. She then claimed her fifth title of the year at the Western &amp; Southern Open defeating Simona Halep. At the US Open, Williams had a chance to win the calendar Grand Slam but was upset by Roberta Vinci in three sets in the semifinals. Williams was the three-time defending champion, but on October 2, Williams withdrew from the tournament to heal her injuries and recapture her motivation.