Defending champion Serena Williams narrowly survived a major scare at Wimbledon, coming from behind to overcome gritty US compatriot Christina McHale in a thrilling second round encounter yesterday.
 The world number one defeated McHale 6-7 (7/9), 6-2, 6-4 in two hours and 29 minutes on Centre Court, only just avoiding what would have been her earliest-ever Wimbledon defeat.
 The six-time Wimbledon champion will face Germany’s Annika Beck for a place in the last 16.
 “It was a really good match. She played great and she always plays great against me,” Williams said.
 “I know mentally no-one can break me. I knew, down a break in the third, that I was going to have to put my mind in it and that’s what I did.”
 Several times throughout the match, Williams was left cursing the bounce of the ball or screaming at the heavens as she struggled to find her form against the world number 65.  McHale was set point down in the 10th game of the first set but challenged when Williams thought she had won the point — and Hawk-Eye technology showed the tiniest sliver of the ball was in, giving the outsider a reprieve.
 McHale recovered and fashioned a few set points for herself before sealing it on the tie break.
 At the end of the first set, a raging Williams was given a warning after smashing her racquet into the ground five times after sitting down, before letting go — the racquet flying into the stomach of a television cameraman.
 Williams, trying to win a Open Era record-equalling 22nd Grand Slam title, broke in the third game of the second set and went on to win it.
 But the champion rode her luck in the third set. McHale hit two double faults to throw Williams a lifeline when she had the chance to go 3-1 up.
 McHale was playing out of her skin, but her first serve deserted her at a critical stage and Williams broke to serve for the set at 5-4 up.
 Williams then rained down three consecutive aces in the final game — she passed the 800 aces at Wimbledon mark during the match — and sealed her place in the round of 32.
 As she left the court, a services steward retrieved the racquet she had thrown away, and the champion duly signed it and gave it to a fan.
 Williams, 34, narrowly escaped what would have been her worst Grand Slam loss since falling to world number 111 Virginie Razzano in the first round at the 2012 French Open.
 Earlier, Juan Martin del Potro admitted he felt “alive again” after the injury-plagued former US Open champion sent Swiss fourth seed Stan Wawrinka crashing out.
On a day when rain caused a 10th delay of the week, forcing organisers to consider playing on the middle Sunday for the first time since 2004, the giant Del Potro shone beneath the Centre Court roof.
 Playing in his first Grand Slam tournament since the 2014 Australian Open, his 3-6, 6-3, 7-6 (7/2), 6-3 second round victory over Wawrinka brought back memories of his stunning 2009 US Open win before a series of wrist injuries pushed him to the brink of retirement.
 The world number 165 from Argentina, who was a semi-finalist in 2013 in what was his last appearance at Wimbledon, next faces French 32nd seed Lucas Pouille.
 “It feels amazing, it’s a great sensation,” said the 27-year-old who has undergone three wrist surgeries in the last two years.
 “I enjoyed the crowd. It’s an incredible feeling, that’s why my hands are still shaking.
 “I feel alive again. After sitting at home for two years, this feels like a second or third career,” added the former world number four.
 Wawrinka, a quarter-finalist in 2014 and 2015, fired 47 winners past Del Potro but was undone by 48 unforced errors.
 “We are happy that he’s back. He’s a great guy off the court. He’s amazing player on the court. He’s big champion,” said Wawrinka.
 Meanwhile, Wimbledon suffered a third day of rain delays.
 Only one minute of action was possible on the outside courts in the first four hours.
The tournament already had a backlog of 16 second round ties and with more rain expected Saturday, organisers admitted that play may take place on Sunday for the first time since 2004 and only the third time overall.
 “Sunday play is being considered but a decision won’t be made until tomorrow,” a spokesman told AFP.
 All men’s second round doubles matches were reduced to best of three sets rather than five in an effort to get the tournament back on the schedule.
Czech 10th seed Tomas Berdych beat Benjamin Becker 6-4, 6-1, 6-2 and French 12th seed Jo-Wilfried Tsonga got past Juan Monaco 6-1, 6-4, 6-3, also in the second round.
Meanwhile, five-time champion Venus Williams reached the Wimbledon last-16, seeing off Russian teenager Daria Kasatkina 7-5, 4-6, 10-8 in a tie featuring a rain stoppage when she held match point.
 Williams, 36, was 7-6, 40-30 up on Kasatkina’s serve in the final set on Court One when the tie was halted by the second rain delay of the day.
 Seventy-five minutes later, the players returned with Wimbledon debutante Kasatkina saving the match point, the second of the day.
 But Williams eventually triumphed at the third time of asking when the 19-year-old dumped a forehand into the net. Williams, the eighth seed, goes on to face Spain’s Carla Suarez Navarro for a place in the quarter-finals.
 “I’m not sure I’ve ever played a 10-8 set. That was pretty intense. All you can think is ‘hold serve’. Easier said than done,” said the American.