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.