LONDON: Novak Djokovic's celebration after finishing off Andrey Rublev in a high-octane Wimbledon quarter-final said it all on Tuesday.

The scoreline may look comfortable enough after the 36-year-old fought back from losing the first set to win 4-6 6-1 6-4 6-3 -- his 33rd successive victory at Wimbledon.

But the seven-time champion knew he had been in a battle against the inspired seventh seed.

"I think today he played terrific tennis," Djokovic said of an opponent he thrashed en route to winning the Australian Open at the start of the year.

"He was putting a lot of pressure, playing very quick, standing close to the line and trying to push me back. It was like a dogfight, to be honest.

"Some points in the match were so long and exhausting. Those games at the end of the third set where basically the match was decided. I felt huge relief when I won the third set."

Djokovic had looked in control but the 10th game of the second set, spanning 15 minutes and including some spellbinding rallies, saw him save three break points and need five set points before finally sealing the set.

Another feisty encounter will be in store on Friday when Djokovic, bidding for a record-equalling eighth Wimbledon title and fifth in a row, faces Italian eighth seed Jannik Sinner.

Like Rublev, Sinner will go after the 36-year-old Djokovic with his aggressive game and the Serbian will need no reminding that he trailed Sinner by two sets in last year's quarter-finals before reeling him in.

"He (Sinner) likes to play on grass. He likes to play on quick surfaces because he likes to be aggressive and take control of the point," said Djokovic. "From both forehand and backhand, he's smashing the ball really, really hard.

"He's a very complete player. Now he's first time in the semis of Wimbledon. I'm looking forward to that challenge. I'm sure that he's going to be very, very motivated to win.

"On the other hand, I am, too."