Djokovic defied heatwave conditions, a fierce early barrage and 30 Kyrgios aces to coolly clinch a seventh Wimbledon crown and grand slam No.21 with a steely 4-6 6-3 6-4 7-6 (7-3) victory on Sunday.

"I'm lost words for what this tournament, what this trophy means to me, to my team and my family," Djokovic said after holding up the Challenge Cup once again.

"I've said this many times - it always has been and will be my most special tournament in my heart, the one that motivated me and inspired me to start playing tennis in a small, little mountain resort in Serbia.

"My parents used to run the restaurant and I was four-and-a-half, five years old and I saw Pete Sampras win his first Wimbledon in 1993 and I asked my mum and dad to buy me a racquet and my first image of tennis was grass and Wimbledon.

"I always dreamed of coming here, just playing in this court and then of course realising this childhood dream and winning this trophy.

"Every single time it gets more and more meaningful so I am very blessed and grateful."

After a rollercoaster, controversy-laden run to the final, Kyrgios had been bidding to become Australia's first men's grand slam singles winner since Lleyton Hewitt reigned at the All England Club in 2002.

He looked on track after taking the opening set with a scintillating display of tennis underpinned by some typically huge serving but also showcasing his trademark tweener and cheeky under-arm serve.

After fining Kyrgios $US14,000 ($A20,500) for spitting on their hallowed grass courts and calling an umpire a disgrace during a tempestuous first week of the championships, All England Club poobahs must have been squirming at the prospect of having to welcome tennis's most volatile star in as a new member.

Djokovic, though, drew on all his vast experience and champion qualities to wear down Canberra's erratic showman physically and mentally in temperatures nudging towards 40 degrees on the sport's most famous centre court.

"Hats off to him. That was a hell of a match. I thought I served well. I put myself in a position to win, but I just wasn't able to play those clutch points well at all today," Kyrgios said.

Kyrgios had been on his best behaviour early on in front of a royal box featuring the Duke and Duchess of Cambridge, Australian greats Rod Laver and John Newcombe, and a raft of other royals and luminaries.

But, after dropping serve for the first time in his career against Djokovic to fall behind 3-1 in the second set, he grew frustrated.

The hot-head was even more agitated after being unable to break back in the ninth game despite holding four break points and having Djokovic 0-40 down as the Serb levelled the match at one set apiece.

Kyrgios threatened to unravel after being given a code violation for swearing in the fifth game of the pivotal third set after claiming to have been distracted while serving by a mouthy spectator in the crowd.

He angrily condemned chair umpire Renaud Lichtenstein's decision as "a joke" and demanded the woman be removed.

"She's drunk out of her mind ... so kick her out," Kyrgios pleaded with the French official.

"The one that looks like she's had about 700 drinks, bro," he added when asked which spectator it was.

Even young Prince George, sitting between William and Kate, was bemused by Kyrgios's behaviour.

There was no let-up, though, as Kyrgios let rip at his box after despairingly being broken at 4-4 from 40-0 up to gift Djokovic the opportunity to serve out the third set.

The top seed duly did so, collected his gear and departed for a toilet break as Kyrgios was left to wonder how the final had so quickly turned.

There were no service breaks in a tense, hour-long fourth set as Djokovic sealed victory in a tiebreaker after three hours, one minute to capture his seventh Wimbledon crown, equalling American great Sampras and Britain's 1880s champion William Renshaw.

Roger Federer, with eight titles at London's SW19, is the only man to have won more.

It's Djokovic's first grand slam triumph since defeating Matteo Berrettini from a set down in last year's Wimbledon final.

The 35-year-old was deported from Australia on the eve of the Melbourne Park major in January for not having the necessary visa and lost to Rafael Nadal in last month's French Open quarter-finals.

Australian Associated Press