Serena Williams has withdrawn from her second-round match with Tsvetana Pironkova. Williams, who was searching for the 24th Grand Slam title of her career, had been struggling with an Achilles injury and was unable to begin the match. вЂњWe realised it wasnвЂ™t the best for me to try to play today,вЂќ Williams told reporters. вЂњIвЂ™m struggling to walk, I felt like I needed to walk with a limp. "An Achilles injury is not one you want to play with as it can get worse." The 39-year-old revealed after her first round win over Kristie Ahn that she had picked up the injury during her run to the semi-finals of the US Open. вЂњI prayed a lot to make these problems disappear,вЂќ Serena told a press conference after the straight sets win over Ahn. Williams, who turned 39 earlier this week, has not won a Grand Slam since January 2017 and has not made it beyond the fourth round at Roland Garros since 2016. The American is considered by many to be the greatest tennis player of all time, with her 23 Grand Slam singles making her the most successful player of the modern era and just one title behind Margaret Court in the list of all-time Grand Slam wins. Williams has vowed to continue her quest for a 24th title after an encouraging year that saw her reach the last four of the US Open. "I love playing tennis. I love competing. It's my job and I'm pretty good at it still… I'm so close to some things and I feel like I'm almost there… that's what keeps me going."