Venus Williams has rejected accusations from her Russian conqueror Elena Dementieva that she played up the effects of a foot injury in their Nasdaq-100 Open quarter-final.

"After the medical break I was thinking she was a good actress because she was moving so much better than before," said Dementieva, who eventually won 6-3, 5-7, 7-6.

"Maybe I should talk to her," Williams said. "I clearly twisted my ankle and I had issues there. But if that's the way she feels, that's fine.

"These days, in order to be a champ and to be a winner you have to play under all circumstances and I think that's what I did. I just tried to ignore it."

Dementieva criticised Williams's conduct when the American seemed to sustain a right foot injury late in the second set.

Williams visibly grimaced when she landed awkwardly after hitting a forehand on her opponent's service game at 5-6 and 30-30.

She had the problem evaluated by WTA trainer Lisa Heller and then took a statutory three-minute injury time-out while her foot and ankle was strapped.

"On her face it looked like she had something very painful, but then she started to move very well," the Russian said.

The medical time-out appeared to upset Dementieva's rhythm, who lost the next two points and with it the second set.

The Russian also went a break down at the start of the third set and had to save a match-point at 5-3 before regaining her composure in time to win the match in the tiebreaker.

"It was a very difficult situation for me because it (the time-out) was in the middle of (a) very important game.

"It was 30-all on my serve and she had a really long medical break, then she started to play and move much better than she was playing in the first set," said Dementieva.

"It took me a few games to come back to the game and get my focus on the court. I'm not sure if she had something (wrong) or not, I can't know, but I think she did everything by the rules."