Eighth seed Juan Martin Del Potro suffered an injury scare after moving into the last 16 at Wimbledon on Saturday with a straight sets win against Slovenia's Grega Zemlja.
Del Potro fell awkwardly chasing down a drop shot in the third set, receiving treatment and taking a medical timeout before wrapping up a 7?5 7?6(3) 6?0 win.
"I will see the doctor after here, because I was going for the dropshot and I twisted my ankle," he told reporters.
"I hyper-extended my knee, as well. It was really painful. I was a little scared at that moment.
"I finish the match very quickly. Now I start to feel something in my knee and my ankle, as well. I will check with the doctor very soon."
Del Potro, who equaled his best performance by reaching the fourth round, will now face Italian Andreas Seppi.