'It's bulls**t': Nick Kyrgios rages at Rafael Nadal over 'ridiculous' tactics

Rafael Nadal has defeated Nick Kyrgios 6-3, 3-6, 7-6 (7/5), 7-6 (7/3) in a stormy and bad-tempered Wimbledon second round encounter on Centre Court on Thursday.

It was Nadal's 50th win at the tournament as he continues his push for a third Wimbledon title and 19th major.

Kyrgios twice served underarm on game point, was handed a code violation for unsportsmanlike behaviour and waged a bitter war of words with umpire Damien Dumusois.

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Increasingly upset with what he perceived to be Nadal's pedestrian pace of play, the 24-year-old described the official as a "disgrace" and said his handling of the explosive tie was "pathetic".

"I have beaten a tough opponent. When he wants to compete well, he is one of the toughest opponents that maybe you can face," said Nadal.

"Normally against me and the top guys, he wants to try hard and when he's doing it, he's very tough."

Kyrgios had famously defeated Nadal as a 144th-ranked teenage wildcard at Wimbledon in 2014.

They have been at opposite ends of the tennis spectrum ever since with the Australian describing the 18-time major winner as his "polar opposite".

Kyrgios had set the tone for the second round clash by stating: "We have mutual respect -- but that's about it."

Nadal had earlier this year accused his rival of a lack of respect for the sport after losing to him in Acapulco.

Toni Nadal, the Spaniard's uncle and former coach, said Kyrgios was "uneducated".

On Thursday, Nadal claimed the only break of the first set in the second game before Kyrgios unleashed his first angry volley at the umpire over the Spaniard not playing to the rhythm of the server as the rules dictate.

"This is bulls**t, he's controlling the tempo, it's ridiculous," he screamed.

His first underarm serve came in the eighth game much to the delight of the crowd who were to jeer his second such tactic to go 4-1 up in the second set.

Kyrgios's mood had not been helped when Nadal took a toilet break after the first set.

It worsened when he dropped serve in the seventh game of the second set and was warned for unsportsmanlike behaviour.

"You have so much power up there," he mocked the umpire.

"You're no-one. You think you're important. You have no idea what's going on. You're a disgrace."

Nadal takes the high ground

Nadal said he was aware of the tantrums on Thursday.

"I have been aware of everything. I was just next to him so I don't want to comment on this," he said.

"Potentially he is a Grand Slam winner."

In the third set, and Nadal gave Kyrgios a lengthy, withering stare-down after the Australian fired a forehand straight at him.

Nadal claimed the tie-break and celebrated with a roar, fist-pump and a leap as the fire died out in Kyrgios.

Although there were no breaks of serve in the final set, it was Nadal who played the more composed tiebreaker.

For Kyrgios, he will reflect on how he lost a match in which he fired 29 aces and 58 winners.

Nadal will face France's Jo-Wilfried Tsonga for a place in the last 16.