Seven-time Wimbledon champion Novak Djokovic is concerned about the danger posed by surging Australian Alexei Popyrin as he seeks to regain his crown.
The 24-time grand slam winner, who still sounds not entirely happy about his form as he recovers from knee surgery four weeks ago, believes the lanky Sydneysider is becoming a complete player.
The pair played at the Australian Open in January when Djokovic prevailed in four sets, but only after the big-serving Popyrin had held set points for a 2-1 lead.
"I saw he won in a five-set thriller today," said Djokovic, commenting on Popyrin's excellent win over Tomas Martin Etcheverry, the 30th-seeded Argentine.
"Big serve. Big forehand. He loves that serve-plus-forehand play. We had a good match, very good match in Australia.
"I think he improved his backhand a lot and his movement, that was maybe not as good in the past. He's becoming a very complete player. Tall guy, he's not afraid to finish the point at the net.
"If he serves well, it's very tough to play him. Anybody on the grass that serves as good as he serves ...
"I guess one of the keys will be in that match how good I will be able to read his serves and get it back in play, make him work for his points. On my end, I'll have to serve well, as well.
"I'm expecting obviously a tough challenge."
Djokovic is clearly not satisfied with his own level after he laboured a little to dispose of the plucky challenge of British outsider Jacob Fearnley.
"I do feel that has an impact on my movement a little bit in terms of the speed," Djokovic said of his continuing recovery after the surgery he needed after worsening his knee trouble at the French Open.
"It's not yet there where I want it to be. I'm kind of late on the balls that I'm normally not late on."
It all offers another golden opportunity for the 24-year-old Popyrin in their third-round contest on Saturday (Sunday morning AEST).
"I think it's important that I serve well. He's the best returner in the world. It's gonna be tough, but I know I can do it," said world No.47 Popyrin.
"I served pretty well in Australia, but in terms of confidence, I'm just gonna go out there enjoy the moment.
"I feel like I do have the game, but I've said that before against big players and have come up short, so I'm gonna keep quiet now!"
