Casper Ruud survived a brief scare against Zhizhen Zhang to move into the fourth round 4-6 6-4 6-1 6-4.
Fourth seed Casper Ruud was the favourite going into the match, and one of the leading players in the tournament given the absence of Rafael Nadal.
On Thursday in his second-round match, he needed four sets against Giulio Zeppieri and there were signs of struggles early on against Zhang.
In the first set, he was 3-1 down against his Chinese opponent, who beat Thiago Tirane in his own second-round tie.
The 26-year-old Zhang is an imposing figure, standing 6ft 4in tall, and had already reached the furthest in his career at any Grand Slam.
Casper Ruud has the Estoril Open to his name so far this season and was a losing finalist in last year’s tournament at Roland-Garros and at the US Open.
The Norwegian struggled to keep his normally strong forehand from breaking down, and half an hour into the first set he complained to the umpire that some balls had become difficult to play as they accumulated clay from the surface.
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Zhang broke again to reach 5-4 and serve for the first set, and he battled to claim it.
Zhang was less steely in the second set and Ruud knew that he would have to push past his own poor form to level at 1-1.
Casper Ruud started to dominate the shorter points compared to the first set, and he was able to win the second set 6-4 to make sure the match would go for at least another two sets.
The Chinese world No. 70 could not maintain his impressive form into the third set and was, if not rattled, unable to resist Ruud and rolled over to go 6-1 down.
Casper Ruud continued to break his opponent with more regular success as he took 13 from 16 points to nudge ahead 4-2 clear on Zhang’s serve, before wrapping things up on his serve.
Speaking on court after the match, he praised his opponent, saying: “It was very tough, I was frustrated at the beginning because I didn’t start as well as I hoped. He was playing well, hitting many winners and I didn’t find any holes in his game.
“At 5-4 in the second set, he played some sloppy shots and I got the break to even the match. That gave me the confidence to start playing better and better. The French crowd helped me a lot today.
“I don’t feel so relaxed, even if I might look it. Maybe I’m a good actor, but every match is stressful and physically and mentally tough. This is the first year I’m coming here to defend a big result, having made the final last year. I feel some extra pressure, but if you say that I look calm, then I’ll take it as a compliment.”
Casper Ruud will face either Nicolas Jarry or Marcos Giron in the next round.