Venus powers on after Ivanovic makes tearful exit

Thigh problem forces out stricken Serb as Williams reaches quarter-finals

The timing could not have been crueller. In hitting her only ace of a match in which she had been consistently outpowered by Venus Williams, Ana Ivanovic felt something give way in her left thigh. After a medical time-out and two more points, the former French Open champion's Wimbledon was over as she retired in floods of tears with Williams leading 6-1, 0-1.

The injury looked only to have brought forward the inevitable. If Ivanovic's victory over Sam Stosur in the previous round had raised hopes that the 21-year-old Serb was recapturing something of the form that had taken her to No 1 in the world rankings 12 months ago, the evidence of her 47 minutes on Court One yesterday suggested that she still has plenty of work to do.

Ivanovic made a fair start, forcing three break points in the opening game, but in no time at all was 5-0 down. The world No 12 has one of the biggest forehands in the game, but she had no answer to the power of the defending champion, who pulled her from side to side with pounding groundstrokes, getting into the net to finish off the points whenever she could. Ivanovic's serve, meanwhile, looked in tatters. Time after time she had to halt her serve in mid-flow after failing to get her ball toss right.

There were sympathetic cheers when Ivanovic finally got on the scoreboard to trail 5-1, but Williams closed out the set in the following game with three service winners.

From 15-40 down at the start of the second set Ivanovic closed to deuce thanks to a Williams forehand error and the Serb's only ace, powered wide of the American's backhand. Ivanovic immediately called for the trainer and took a medical time-out to have her thigh strapped, but was clearly struggling to move when the match resumed. Ivanovic won the next two points and the game – ironically enough, it was the only time in the match when she won four points in a row – but knew she could not continue.

The tears were already flowing by the time Ivanovic shook hands with Williams at the net and her eyes were still moist when she arrived for her post-match press conference more than an hour later. "When I landed [after the ace] I just felt a sharp pain in my inner thigh and I haven't been able to step on my leg ever since," she said, fighting back the tears. "It's obviously very disappointing, especially as I felt my form was getting better and better."

Despite the fact that Williams had taken the first set with plenty to spare, Ivanovic found reasons for optimism. "If I had managed to break in the first game I think the first set would have looked a lot different," she said. "Even though the score was not indicating it, I thought it was pretty close. She wasn't making many mistakes.

"It was frustrating because I felt good out there. I was playing better each match. I just thought it was a great challenge for me today to play against someone like Venus."

Since winning last year's French Open Ivanovic has failed to go beyond the fourth round of five successive Grand Slam tournaments. In the run-up to Wimbledon she parted company with Craig Kardon, her coach of only four months. She was never the best of movers and often appeared uncomfortable at the net, but now she seems also to have lost the confidence in the big groundstrokes that were the foundation of her success.

By the time yesterday's match finished there was more tape on the court than on a cutting-room floor. Ivanovic had started with tape on her right knee, while her heavily strapped left thigh matched Williams' right knee. Although the defending champion did not seem restricted in her movement, her knee has been strapped since the second round and she has clearly been in pain. "I'm doing everything I can for my knee," Williams said after the match. "And this is Wimbledon, so it doesn't matter how much pain I'm in, I'm going to keep playing." Asked how bad the pain was, Williams replied: "I'm still smiling."

The world No 3, who now plays Poland's Agnieszka Radwanska in today's quarter-finals, was delighted with the way she had taken command of the first set. "I'm a control freak," she said. "I love controlling. I'm used to that. That's how I was taught to play, so I was pleased to go out there and play well against someone as good as her. She didn't have a lot of opportunities in that first set – and not because she wasn't playing well. I think I was just on top of the ball."

If you count yesterday's second set, Williams has now won 30 sets in a row here. The last time she dropped a set was in the third round two years ago, against Japan's Akiko Morigami. It might take a dodgy knee to end that sequence.