My knee flared up – Wawrinka reveals reason for retirement

Swiss veteran Stan Wawrinka said he was unable to continue at Open 13 Marseille after succumbing to his troublesome knee Thursday.

The three-time grand slam champion was forced to retire against Ilya Ivashka when trailing 6-4 1-1 at the ATP 250 event.

Wawrinka has been plagued by knee issues since undergoing surgery following his first-round loss at Wimbledon, missing the second half of 2017, while he was beaten in round two at the Australian Open last month.

Talking about his early withdrawal, the 32-year-old – who was upstaged by world number 259 Tallon Griekspoor at the Rotterdam Open – said his left knee flared up in the first set.

"At 3-3 I hit a forehand volley and it hurt the knee a bit. I felt that it was very tense," Wawrinka told the tournament organiser's website. "After that I simply couldn't flex it."

Wawrinka continued: "When the knee becomes tenser, when it puts pressure on the knee cap, you shouldn't force it.

"That's when you make things worse. These are difficult times. It's a long process but you need to take a step back from everything that's happening."