Top seed Novak Djokovic cruised into the Wimbledon third round after three-time Grand Slam champion Stan Wawrinka lost to American Reilly Opelka.

Serbia's Djokovic, 32, needed just one hour and 33 minutes to beat American Denis Kudla 6-3 6-2 6-2.

Ex-world number three Wawrinka had the upper hand against 2015 boys' junior champion Opelka after three sets.

But 6ft 11in Opelka fought back with ferocious serving to edge a three-hour match 7-5 3-6 4-6 6-4 8-6.

Djokovic is the defending champion at SW19 and once again considered the man to beat as he chases a fifth title at the All England Club.

The 15-time Grand Slam winner was never threatened against Kudla, producing another efficient performance on Centre Court against the world number 111.

Djokovic, who has added former champion Goran Ivanisevic to his team for the tournament, played a high level throughout as he moved well and relentlessly tested Kudla.

"I'm pleased with my game overall. There were some moments in the match where I could have done better, I dropped my serve a couple of times," said Djokovic, who also beat Germany's Philipp Kohlschreiber in straight sets on Monday.

"But it was a solid performance, I was returning well, mostly I was serving well and I was holding a high percentage of first serves."

Djokovic will play Poland's Hubert Hurkacz - little over a month since the Serb beat him in the French Open first round - next on Friday.

Opelka 'deserved' win, while Anderson, Raonic & Auger-Aliassime go through

Opelka is the joint-tallest-ever ATP-ranked player, along with Ivo Karlovic. His 142mph (228kph) serve against Wawrinka was the fastest of the Championship so far.

After the match the Florida-raised player, who won his first ATP title in February with victory at the New York Open, bristled when asked how tall he was.

"I have answered this question, like, 150 times," he said. "It's the same as it was yesterday, and, I don't know. Close, 6'11", 7'0". Not sure."

Wawrinka added: "Against those big servers you know you're not going to have a lot of chances and you get under pressure a little bit more.

"At the end he went for it. He went bigger than me, more aggressive, and he deserved to win".

Opelka, 21, will face Canadian Milos Raonic in the third round.

The 2016 finalist, who is seeded 15th, defeated Dutchman Robin Haase 7-6 (7-1) 7-5 7-6 (7-4).

South African fourth seed Kevin Anderson, who lost to Djokovic in last year's final, advanced with a 6-4 6-7 (5-7) 6-1 6-4 victory over Serbia's Janko Tipsarevic.

Russian Karen Khachanov got through a tricky test against Queen's champion Feliciano Lopez.

The 10th seed came from a set down to win 4-6 6-4 7-5 6-4 and make it through to the third round for the third year in a row.

Fellow Russian Daniil Medvedev, the 11th seed, defeated Australian Alexei Popyrin 6-7 (6-8) 6-1 6-4 6-4, while Canadian teenager Felix Auger-Aliassime progressed by beating France's Corentin Moutet 6-3 4-6 6-4 6-2.

Coco Gauff's fairytale introduction to Wimbledon continued with a second-round victory that belied her years over Magdalena Rybarikova.

The 15-year-old American qualifier needed just one hour nine minutes to beat her Slovakian opponent 6-3 6-3 under Court One's new roof.

Gauff, who beat five-time Wimbledon champion Venus Williams on Monday, will play Slovenia's Polona Hercog next.

"I'm still shocked I am even here," Gauff told BBC TV.

"I played well on pressure points, she was serving amazing. I've not been able to relax, there is so much going on.

"I believe I can beat anyone across the court."

At such a tender age, Gauff is only eligible to play 10 tournaments at professional level between her 15th and 16th birthdays yet she appears to be taking the grand occasion of Wimbledon in her stride.

Earlier on Wednesday, she had trained briefly under the gaze of 18-time Grand Slam champion Rafael Nadal before being approached for a chat by Roger Federer, an eight-time winner in these parts, more than six hours before she finally got to play.

After a late court switch, the match finally got under way just after 20:00 BST, but Gauff looked at home straightaway against the world number 139, who reached the semi-finals at Wimbledon two years ago.

She broke 30-year-old Rybarikova's serve to love to go 4-2 up, losing just five points on her own serve throughout the entire first set.

Rybarikova, somewhat unsettled by the crowd's fierce support for Gauff, had her serve broken once again early in the second set.

But, showing glimpses of the form that saw her formerly become the world number 17, Rybarikova started to rally, twice defying Gauff on break point.

Yet this was always to be Gauff's night, seeing out the win by breaking serve once again.

More to follow.

Britain's Kyle Edmund says he must improve his fitness after squandering a two-set lead to lose to Fernando Verdasco in the Wimbledon second round.

The British number one was three games from victory before a slip and fatigue derailed him in a 4-6 4-6 7-6 (7-3) 6-3 6-4 loss.

British women's number two Heather Watson was also knocked out after being outclassed by Anett Kontaveit 7-5 6-1.

Five other Britons will seek to reach the third round on Thursday.

Cameron Norrie, Dan Evans and Jay Clarke are still in the men's draw, while British number one Johanna Konta and Harriet Dart are the remaining home hopes in the women's singles draw.

"It was a long match, quite a physical match," Edmund, 24, said. "The sort of physical intensity that I showed in the first part of the match gradually just declined. I was not able to keep that level up.

"I should have probably finished the match in the first place in the first part of the match, having obviously a two-sets-to-love lead and a break."

Edmund unravels after slip

Edmund, who reached a first Tour-level grass-court semi-final at Eastbourne last week and said he believed he could win Wimbledon, began confidently against 35-year-old former world number seven Verdasco.

After pushing the Spaniard hard on his serve before getting the break in the 10th game of the opening set, he was handed the second set in bizarre fashion when Verdasco decided not to chase after a lob he thought was going wide.

The ball bounced in and Edmund's roar was repeated by a packed Centre Court crowd.

But that was just about the last bit of luck Edmund had, squandering an early break to find himself taken into a third-set tie-break.

A slip towards the end of the third set left him walking gingerly and he called on the physio for treatment on his right leg and back after the tie-break.

"When you slip, it's just a bit of a shock," Edmund said.

"It didn't hold me back at all. I physically was not able to keep going with, like, the power and reaction and stuff."

Edmund, who withdrew from his second-round match at the French Open in May with a left knee problem, was once again let down by his body.

His movement became laboured and his shoulders dropped as the momentum swung in the favour of Verdasco, who wrapped up victory on the first of three match points.

'I've got to put some more hours in'

Edmund says he will work on improving his strength so that he can deal better with longer matches.

His season has been disrupted by the left knee problem that cut short his 2018 season but he said he did not want to use that as an excuse.

"Now I've got to try and put some more hours in. We talk about [matches lasting] three and a half, four hours, getting to that level. I've got to do that," he said.

"I've got to be able to play at the intensity I started the match for longer. These are not excuses. These are just stuff I've got to get a bit better at.

"I was in a position to win, and didn't."

Analysis

BBC tennis correspondent Russell Fuller

Edmund says his third set slip had absolutely no bearing on the result - admitting instead that he was just not able to maintain his physical intensity of the first couple of sets.

A lack of endurance was also an issue at last August's US Open. Regular bouts of illness had held him back, and it was hoped the removal of his tonsils had solved the problem.

But by then he had developed a knee problem which has restricted him to just 22 matches this year.

His next stop will be the gym: Edmund says he hopes to make the most of the three and a half weeks before his next tournament in Washington.

Gulf in rankings shows in Watson defeat

Estonian 20th seed Kontaveit was always going to be a difficult opponent for world number 122 Watson, who had suffered first-round exits at her previous three grass-court events.

But the Briton started well in breezy conditions, breaking in the opening game and then holding before being pegged back for 2-2. They matched each other for the rest of the set before Kontaveit stepped up a gear at 5-5.

The Estonian won the next two games to love, with Watson hitting long to hand her the first set.

From then on Kontaveit was uncompromising. She went a double break up in the second and made Watson run around the court, capitalising when the Briton's errors crept in.

"I thought today in general I was too defensive," Watson said. "I didn't use my variety enough, coming to the net.

"I'd say the first two games started well. That first set, I just felt like I had so many chances, but wasn't able to play aggressive tennis and get there. I sort of went on the back foot, just made too many errors.

"After that first set, I don't feel that I changed a lot. I just feel like she relaxed and really stepped up her level, didn't give me a look in at all."

Kontaveit, whose only WTA title was won on grass, will face Czech Karolina Muchova for a place in the third round.

Mixed fortunes for Britons in doubles

There were plenty of other Britons in action when the doubles began on Wednesday, with Cameron Norrie among those to reach the second round.

He and Spanish partner Jaume Munar beat fellow Briton Dom Inglot and American Austin Krajicek 4-6 6-3 6-4 6-7 (11-13) 6-3.

Joe Salisbury and American partner Rajeev Ram, who were runners-up to Andy Murray and Feliciano Lopez at Queen's, also progressed with a 6-3 6-4 6-2 win over Malek Jaziri and Radu Albot.

They are joined in the next round by Ken Skupski and Australian John-Patrick Smith after their 6-2 6-4 6-2 victory over the all-British pairing of Jay Clarke and James Ward.

But there were defeats for Jack Draper and Paul Jubb, Freya Christie and Katie Swan, Luke Bambridge and Jonny O'Mara, Sarah Beth Grey and Eden Silva, Harriet Dart and Katie Dunne, and Naomi Broady.