Tsitsipas gets delayed Miami campaign off to winning start
The Greek had a first round bye and then had a walkover win in the second round when Richard Gasquet pulled out with injury.
"It has almost felt like a vacation this past week, staying in Miami. I glad I got started. It was a difficult match against an opponent who has played good tennis against good opponents in the past," said Tsitsipas.
Tsitsipas has not be on court much in recent weeks - he withdrew from Acapulco due to a shoulder injury and was beaten in the opening round in Indian Wells
The rest has however helped Tsitsipas to recover a little from his injury and although he was not at his sharpest, he did enough to book his place in the fourth round against Karen Khachanov.
Tsitsipas broke at 4-4 in the third set to make sure of his progress against the Chilean, who enjoyed plenty of support from the South Florida crowd.
"I am just going to enjoy this victory. It has been a difficult road to healing in the past few weeks, but I am happy that things are getting better," he said.
Khachanov defeated Czech Jiri Lehecka 6-2, 6-4 to reach the Miami last 16 for the first time.
Exciting American Frances Tiafoe was tipped by many observers to go deep in the tournament but he fell 6-3, 6-4 to Lorenzo Sonego in a game disrupted by a second set rain delay of over an hour.
French qualifier Quentin Halys hit 15 aces as he beat American Mackenzie McDonald 7-6 (7/2), 6-3.
Halys had never won a match at ATP 1000 level prior to this tournament but has beaten Spain's Pedro Martinez and Australian Alex de Minaur before taking out McDonald.
"I think I'm just the same player, I am just more confident, I know exactly what I have to do on court and I am very confident in my serve," Halys told AFP.
The 26-year-old said he has sharpened his mental approach to the game, handling better the disappointment of missing out on break opportunities against McDonald in the second set.
"I was still very focused, very positive after those games. Maybe in the past I was negative with myself and I am more positive now, maybe that is the key," said Halys who is ranked 79th in the world.
Cerundolo was knocked out of Indian Wells in straight sets by Canadian Auger-Aliassime two weeks ago, but it was a very different game on the faster courts in South Florida.
The 25th-seeded Argentine was on top from the outset, taking the first set 6-2 and he kept his nerve to triumph 7-5 in the second.
Miami is a happy hunting ground for Cerundolo, who made a surprise run to the semi-finals last year, and he relished the vocal support from his fans in the crowd.
"That was another important win for me, I think I played really good from beginning to end," he said.
"It is super nice to play here, a lot of Argentinians, a lot of people, so I really enjoyed it. Last year was amazing, so I'm really excited to be in the round of 16 again and to try to keep winning," he added.
Adrian Mannarino beat seventh-seeded Pole Hubert Hurkacz and American qualifier Christopher Eubanks defeated Gregoire Barrere in straight sets.
