LONDON - Three-time champion Novak Djokovic admitted on Saturday that he has rediscovered his passion for tennis after making Wimbledon's fourth round for the 10th time.

The former world No 1 eased to a 6-4, 6-1, 7-6 (2) win over Ernests Gulbis of Latvia to set up a last-16 clash with unseeded Adrian Mannarino of France.

It's a far cry from 12 months ago when Djokovic was bundled out in the third round by Sam Querrey.

That defeat triggered a sharp decline which saw the Serb relieved of all four of the majors he had held at the same time.

On Saturday, his former coach Boris Becker said he had witnessed enough in the first week of Wimbledon to confirm that Djokovic is back in love with the sport.

"Boris knows me very well. So he's right when he says that the passion is back," said Djokovic.

"I've been feeling better on the court in the last couple of months.

"But especially on the grass court this season so far, every match that I've played, I felt very comfortable.

"When you're playing well, then you're feeling well, then you're even more motivated and passionate to see how far it can take you."

Second seed Djokovic will take a 1-0 career lead over left-handed Mannarino into Monday's last-16 clash.

Twelve months ago he defeated the Frenchman in the second round.

"I'm delighted with the performance. I thought I raised the level of tennis," said Djokovic after making the second week without dropping a set.

"Comparing to the first couple of matches and the last couple of weeks, I think this was the most focused I was on the court."

Gulbis, now ranked at a lowly 589 after once reaching No 10 in the world in 2014 when he defeated Roger Federer on his way to the French Open semifinals, fired 37 unforced errors to Djokovic's meager 12.

"It's not easy obviously playing on grass against a big server like that," said Djokovic of his childhood friend Gulbis, who he has now defeated six times in seven meetings.

"I'm very pleased with the way I've felt, the way I've played."

Agence France-Presse