Alex de Minaur has learned the hard way how to pace himself in tournaments and one of the biggest lessons is that it is not just about preserving physical energy.

The Australian number one admits he used to beat himself up, picking holes in his performance even when winning. All that negative energy gradually drained him just as much as a long game could deplete his physical reserves.

So after a second Wimbledon performance that left a bit to be desired he was still content, describing his 109-minute 6-3, 6-2, 6-2 dismissal of French veteran Adrian Mannarino as "clean", even as he said: "I think I've got more to give."

Mannarino can be a difficult opponent, but he did not play well. Nor did De Minaur reach the standards he can, but he was better than in his nervy first-round win over Roman Andres Burruchaga and feels he will continue to improve.

"One of the things I have learnt is, in the early stages of my career I was a little bit too tough on myself, wanting to start these tournaments at the highest level possible," de Minaur said.

"And often I would just get frustrated and let negative feelings not allow me to get through some tough moments.

"Ultimately, the first week is all about trying to survive and advance. It doesn't matter how you do it, whether it's pretty, whether it's ugly, whether you play your best match or your worst match. As long as you get through, you give yourself a chance.

"And I feel like once the first week finishes, that second week is a little bit of a reset, and then it's, 'OK, now you've got to shift the mindset, now you're playing to go deep or win the tournament'. That's the two mindsets.

"The first week, it's surviving and finding ways, digging deep, no matter what is thrown at you. And then the second week is where you can enjoy yourself a little bit more."

De Minaur now meets American Zachary Svajda, who he has never faced, and insists that remains as far as he is looking, even after Ben Shelton's exit opened a clear path all the way to a first grand slam semi-final.

"The way I look at it is, I'm in the third round. I want to go deep, of course. I want to give myself that opportunity," he said.

"But as much as I would love to just jump a couple steps and put myself already in the final, there's lots of matches and lots of tough moments that I've got to get through.

"Seeds lose. Upsets happen. This sport is unpredictable."

De Minaur is the only Australian remaining in the men's side of the draw, after James Duckworth went down fighting to Italy's Flavio Cobolli 7-6 (7-4), 3-6, 7-6 (6-3), 6-1.

AAP