Serve saves Serena while her forehand jets off to Hawaii

LONDON (Reuters) - Serena Williams needed 20 aces on Thursday to compensate for a forehand she said had taken a vacation in an epic Wimbledon semi-final victory over Russian Elena Dementieva.

Williams fought off a match point when she was down 4-5 30-40 on her serve in the deciding set. She held on to win 6-7 7-5 8-6 in the longest Wimbledon women's semi-final of the open era, stretching over two hours 50 minutes.

"I certainly owed this win to my serve," Williams told a news conference as she savored the prospect of a fourth Wimbledon final against sister Venus.

"When it was key and it was time for me to hold serve, I was able to hold serve. My forehand didn't show up today, I think he went to Hawaii.

"But you know it's always good to win when one of your strokes is on vacation.

"I definitely had to dig deep, because I was playing a player that didn't give me an inch, didn't make too many errors, was playing 100 percent. It's definitely one of my more dramatic victories."

Williams paid tribute to her opponent, who matched her stroke for stroke in the first set tiebreak and did not get the benefit of several desperately close line calls.

"I definitely think she played her best game, I've never seen her serve so well in my life. She definitely played her best, personal tennis today," Williams said.

(Editing by Miles Evans)