Alexei Popyrin will depart Wimbledon with the praise of his conqueror Novak Djokovic ringing in his ears and fresh belief that he can mix it with the very best in tennis.

The Sydneysider's big game troubled the great Djokovic in the early stages of their third-round clash on Saturday to the point that the Serbian maestro admitted Popyrin was a threat to any player.

Though he eventually succumbed in four sets to the relentless excellence of the seven-times champion, just as he had in their Australian Open clash in January, Popyrin felt his performance showcased his considerable improvement over the past year.

"I didn't expect anything less than what we experienced on the court today from Alexei," Djokovic told the Centre Court crowd after his 4-6 6-3 6-4 7-6 (7-3) victory.

"With that serve and powerful forehand, he's dangerous on any surface."

Popyrin said although he had been left with the same gnawing sensation of frustration he'd felt in Melbourne, his performance had persuaded him that he's edging ever closer to matching the elite.

Asked what positives he took out of a week in which he had also defeated 30th seed Tomas Martin Etcheverry, the 24-year-old said: "I know that I can play on a grass court, that I can battle with one of the greatest of all-time on grass-courts.

"I can take sets, I can take him to a tie-break, I can battle with him.

"And if you asked me this time last year if I could battle with these guys in the same way, I would probably say no."

Popyrin will clamber a few more places higher from his current No.47 in the rankings but knows he still has to avoid lapses in concentration, conceding a drop in his intensity in the second set helped Djokovic recover.

"I've taken it to him twice, and I've had chances both times. The first time could have been seen as a fluke, but this time I took the first set and had break points in the second, and it was all on my racquet up until that point," shrugged Popyrin.

"Then I kind of just let my foot off the pedal a little bit, kind of lost focus. I'm a bit bummed, but I'm close, I feel very close."

Popyrin certainly looked poised and confident in his first outing on the most famous stage in tennis.

"I was a set up with break points. If I capitalise on those, then who knows how it goes?" he shrugged.

"Losing again will gnaw at me like the Melbourne defeat did. Tie-breakers can go either way and I didn't put away one ball and he made me pay - that's the world's best, that's what they do."