Novak Djokovic fired a warning to his Wimbledon title rivals by easing past Australian Thanasi Kokkinakis in a flawless display, and then vowing to get even better.

The defending champion had been unconvincing in his 6-3 3-6 6-3 6-4 victory over Korean Kwon Soon-woo in what was his first match on grass since last year's final.

But, ominously for the rest of the men’s draw, Djokovic looked more like the player who has not lost a match here since 2017 as he effortlessly saw off world number 79 Kokkinakis 6-1 6-4 6-2.

The 35-year-old is vying for a fourth straight title to move level with Pete Sampras on seven, and within one of men’s record-holder Roger Federer. On this form it is hard to see anyone stopping him.

After completing victory in exactly two hours, Djokovic said: "I’m happy with my performance today. A really high-quality performance.

"I must say I’m quite pleased with the way I’ve raised the level of tennis in two days.

"Hopefully I can keep that trajectory, just thinking about the next challenge and hope things will get better as the tournament goes on."

Andy Murray was defeated by big-serving American John Isner 6-4 7-6 (7-4) 6-7 (3-7) 6-4.

Two-time champion Murray failed to reach the third round for the first time as the towering Isner secured a first career victory over him at the ninth attempt.

Murray threatened another of his late-night comebacks from two sets down when he won a third-set tie-break, but Isner stood firm in the fourth set.

Forgetful Frenchman Ugo Humbert left his rackets behind ahead of his match with Casper Ruud.

Despite a rain delay of more than an hour and a half, the 24-year-old world number 112 still managed to arrive on Court Two without the tools of his trade.

But after sending someone to the locker room to fetch them, Humbert went on to knock out the third seed.

Norwegian Ruud, the French Open runner-up, is no fan of the grass courts and bowed out 3-6 6-2 7-5 6-4.

Cameron Norrie survived a big scare to make it through to the third round after a 6-4 3-6 5-7 6-0 6-2 victory over Juame Munar.

The friendly nature between the former doubles partners may have ended had the Spanish right-hander maintained his level throughout an exciting back-and-forth battle on Court One.

Spanish teenager Carlos Alcaraz, the youngest man in the draw, claimed a 6-4 7-6 (7-0) 6-3 win over Dutchman Tallon Griekspoor.

Alejandro Davidovich Fokina suffered an ignominious exit as he was given a point penalty while facing match point against Jiri Vesely for hitting a loose ball out of the court, with the Czech player prevailing 6-3 5-7 6-7 (2-7) 6-3 7-6 (10-7).