Tennis Roundup: Nadal advances in Barcelona; Azarenka ousts Zvonareva

World number two Rafael Nadal dropped a set at the Barcelona Open for the first time in four years before advancing to the last 16, beating Argentine Leonardo Mayer 6-7(7), 6-4, 6-2 on Wednesday.

The Spaniard surrendered a 5-3 lead in the first set and then spurned two set points in the tiebreak, which Mayer, ranked 63 in the world, edged thanks to an impressive crosscourt forehand winner.

Nadal, who has won the Barcelona Open a record 11 times, had not lost a set in the tournament since being beaten by Fabio Fognini in the last 16 in 2015. He had won 30 sets in a row until he met Mayer.

Nadal was in danger of losing two consecutive matches on clay for the first time in his career following defeat in the Monte Carlo Masters semi-final to Fognini, but he bounced back immediately by breaking his opponent in the second set opener.

Nadal, who was playing on a court named after him, broke the Argentine twice more in the decider to set up an all-Spanish last 16 tie with David Ferrer.

"It wasn't the best start, I wasn't feeling at my best out there but I found a way to keep going and to win the match," Nadal told reporters.

"All games are dangerous, especially when you lose the first set, anything can happen. You have to look at things in the most positive way and the most positive thing is to be able to play again tomorrow."

Ninth seed Denis Shapovalov was knocked out by Chilean Christian Garin 7-5, 6-2, while Bulgarian Grigor Dimitrov made it through after seeing off Spaniard Fernando Verdasco 6-2, 6-7(4), 6-3.

Ferrer beat Frenchman Lucas Pouille 6-3, 6-1 while Argentine Guido Pella beat six-seed Karen Khachanov in straight sets.

Lucky loser Roberto Carballes Baena beat compatriot Nicola Kuhn in three sets after Fognini withdrew from the tournament following injury concerns after practising earlier in the day.

Jet lagged Azarenka ousts Zvonareva, Kvitova through to Stuttgart quarters

Belarusian Victoria Azarenka made a winning return to Stuttgart with a 7-5, 6-4 victory over Russia's Vera Zvonareva in what was an engrossing battle in the first round of the Porsche Tennis Grand Prix on Wednesday.

Azarenka, a former world number one, was pushed in the opening set, especially by Zvonareva's first serve, but fought back to break her four times in the match. The last time the pair met was in 2011 when they were both ranked in the top 10.

"We're both in completely different stages of our careers, we're both moms," Azarenka said.

"I think I'm playing better than I used to before, I believe I'm much more of a complete player than I used to be. I'm in the process of building my game up again."

The 29-year-old, a two-times Australian Open champion, also had to overcome jet lag after competing in the Fed Cup semi-final in Australia at the weekend.

"I have no idea right now of the time or what's happening," she told reporters. "The flight from Australia was so long I felt like it was never going to end! It was a huge challenge for me today and I'm very happy with the way I handled it."

Azarenka will take on fourth seed and defending champion Karolina Pliskova next for a spot in the quarter-finals.

World number three Petra Kvitova, who received a bye to the second round, cruised through to the quarter-finals with a 6-1, 6-4 win over Belgian qualifier Greet Minnen in a game where she covered the court well and anticipated shots to take a quick lead.

Minnen was no match for Kvitova in the first set but found her groove in the second to test the Australian Open runner-up. However, it was too little too late for the 21-year-old as Kvitova wrapped up the match in 73 minutes.

Earlier, Switzerland's Belinda Bencic started the tournament strongly with a 6-2, 6-4 victory over qualifier Mandy Minella.

Bencic, who ended a four-year title drought in February when she beat Kvitova in Dubai, struck 24 winners with her aggressive returns dominating the Luxembourger. The result pits Bencic against sixth seed Kiki Bertens.

Last year's semi-finalist Anett Kontaveit of Estonia breezed past France's Caroline Garcia with a 6-4, 6-3 win while Donna Vekic beat Giulia Gatto-Monticone 6-1, 7-5 to advance.

2011 champion Julia Goerges' first match was cut short by injury with the German forced to retire when she was trailing 4-0 in the final set to Anastasia Pavlyuchenkova. Goerges had taken the first set 6-4 before the Russian took the second 6-2.

Andy Murray 'optimistic' he can play this year, says mother Judy

Andy Murray is "cautiously optimistic" he will be able to play tennis again this season after successfully undergoing hip surgery, his mother Judy has said.

The three-times Grand Slam champion said at this year's Australian Open that constant pain in his hip had brought him to the verge of quitting tennis but revealed last month that he was pain free after the procedure in January.

Murray posted an Instagram video of himself on an outdoor court earlier this month, describing the footage of him hitting a tennis ball for the first time since the surgery as "a start".

He followed that up with a video of himself playing a round of golf that reinforced the message that he was on the mend.

"It's still early days so we will have to wait and see what happens. He is cautiously optimistic about getting back on the match court perhaps at some point over the summer," Judy was quoted as saying by British media.

"He was told not to do impact work, which basically means running around the garden hitting a ball, for three months but he's been hitting against a wall from a static position."

Murray hoped to make his comeback at Wimbledon and said in March that he would consider playing doubles because it would put less stress on his hip.

The 31-year-old twice Wimbledon champion has compared his situation to that of American doubles player Bob Bryan, who returned to competitive tennis 5-1/2 months after undergoing a similar procedure.