By Neil Maidment
LONDON (Reuters) - World number one Serena Williams survived an almighty scare at Wimbledon on Friday, battling back to beat inspired Briton Heather Watson in three sets and stay on course for a 21st grand slam title.
Williams, who has lifted this year's Australian and French Open crowns, was forced to dig deep in front of a raucous home crowd after an error-strewn showing against the superb Watson, recovering from 3-0 down in the final set to win 6-2 4-6 7-5.
The 33-year-old will face her sister Venus in the last 16 -- their 26th career meeting -- as she continues her bid for a sixth Wimbledon crown.
"I have had some tough losses but that was probably my toughest match. I think she played unbelievable and should have won the match," the American told reporters.
"She could get beyond the top 20, she is playing really well... She was playing so good there was nothing I could do."
The signs looked ominous for 59th-ranked Watson early on after being swept aside in the first set but the 23-year-old bounced back in the second, forcing Williams into a string of wayward shots as she matched up to her more powerful opponent.
Watson reeled off six games in a row with three service breaks to level the match and race into a shock 3-0 lead in the decider, raising the prospect of a first British female victory over a reigning world number one since Sue Barker beat Chris Evert in 1979.
"It would have been a lot better if I won," Watson said.
"But I hope I showed them (the crowd) that I fought for them and it is not going to be a walk in the park for anyone who plays me."
Having dropped her first set of the tournament, a visibly frustrated Williams roared back with four straight games in trademark powerful fashion before the two traded blows as Watson scurried around Center Court to keep pressure on the American.
Watson was twice just two points away from the biggest victory of her career when she served for the match at 5-4, only for Williams to show the grit and guile behind many of her successes to prevail in two hours and 15 minutes.
Williams has now won 24 grand slam matches in a row but will hope for more consistency in the fourth round.
Demonstrating an erratic afternoon's work, she produced three times as many errors as Watson in the match but more than double the number of winners.