Bastad: World No 1 and six-time Wimbledon champion Serena Williams pulled out of the Swedish Open with an elbow injury on Thursday and set her sights on recovering for the US hardcourt season.

Serena in action during her Bastad opener against Ysaline Bonaventure

The 33-year-old was set to play Klara Koukalova in the second round having defeated Ysaline Bonaventure of Belgium 6-2, 6-1 in her opener on Wednesday at the claycourt event she won in 2013.

"I was having some pain in my right elbow," Williams said. "I felt it a little bit in my match yesterday, and then it got better, but then this morning I really couldn’t hit serves, and if I’m not able to hit serves that could definitely be a problem.

"The main thing is that we don’t want it to get worse, we obviously want it to heal. Unfortunately I haven’t had time to heal. I’ve been going, going, going, playing tournaments I love, and coming here has been such a great joy, but unfortunately it’s not going to heal if I keep playing."