Rio Open 2025 Day 5: Men's singles predictions ft. Francisco Cerundolo vs Alexandre Muller, Sebastian Baez vs Tseng Chun-hsin

Players will duke it out in the quarterfinals on Day 5 of the Rio Open 2025. Brazilian teen star Joao Fonseca won the Argentina Open last week, and was expected to continue his winning streak here as well. Unfortunately, the Rio native's journey came to a swift end as he failed to cross the first hurdle.

Second seed Lorenzo Musetti's withdrawal due to an injury also dealt another blow to the tournament. However, top seed and World No. 2 Alexander Zverev has shined on his debut here. He has advanced to the quarterfinals with wins over Bu Yunchaokete and Alexander Shevchenko.

Zverev previously finished as the runner-up at the Australian Open a few weeks ago, going down to defending champion Jannik Sinner in the final. He's on the hunt for his first title since winning the Paris Masters in November 2024. As the highest-ranked player in the draw, he will be the favorite to go all the way.

Defending champion Sebastian Baez, along with Francisco Cerundolo, are two of the other big names left in the draw. As the tournament nears its business end, here's a look at the predictions for three of the four quarterfinal matches set for Day 5 of the Rio Open:

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#1. Sebastian Baez vs Tseng Chun-hsin

Tseng Chun-hsin has reached his biggest career quarterfinal at the Rio Open 2025. (Photo: Getty)

Baez commenced his title defense at the Rio Open with a 6-3, 7-5 win over compatriot Roman Andres Burruchaga. He faced another compatriot of his, Mariano Navone, in the second round and beat him 6-4, 1-6, 6-3 to reach his first quarterfinal of the season. It also marked the first time he won back-to-back matches this year.

Tseng came through the qualifying rounds and upset third seed Alejandro Tabilo 6-3, 7-5 in the first round. He rallied from a set down to beat home favorite Thiago Monteiro 6-7 (4), 6-3, 7-6 (4) to reach his first quarterfinal at the ATP 500 level, and the second of his career.

Tseng's win over Tabilo was his first over a top 50 player, and his run in Rio has ensured his return to the top 100 of the rankings next week. Baez has found his footing after a dismal start to the season, and has made it to the halfway stage of his title defense here.

Given where they stand based on their rankings and accomplishments, Baez is the clear frontrunner here as a top 40 player and the winner of six titles. However, Tseng has played some inspired tennis this week, so one can't write him off that easily.

Predicted winner: Sebastian Baez

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#2. Jaime Faria vs Camilo Ugo Carabelli

Jaime Faria at the Rio Open 2025. (Photo: Getty)

Faria fell in the qualifying rounds of the Rio Open but got a second shot as a lucky loser. He beat Marcelo Tomas Barrios Vera 6-2, 7-5 in the first round, and survived a tough fight from Jaume Munar to beat him 6-4, 2-6, 6-3 in the second round.

Ugo Carabelli also lost in the qualifying rounds at first but found a place in the main draw as a lucky loser. He fought from a set down to upset seventh seed Pedro Martinez 4-6, 6-3, 6-3 in his opener, then defeated Damir Dzumhur 6-4, 6-4 in the next round.

Both have made the most of their second chance in Rio. This is just the second all-lucky loser battle in the history of the ATP Tour. Both have advanced to their first quarterfinal at the ATP 500 as well, and will be keen to capitalize on this golden chance to gain some valuable points.

Faria gave a good account of himself earlier this year when he reached the second round of the Australian Open, and even won a set against Novak Djokovic before losing to him. If he plays at that level once again, then he could certainly upstage his opponent here.

Predicted winner: Jaime Faria

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#3. Francisco Cerundolo vs Alexandre Muller

Francisco Cerundolo at the Rio Open 2025. (Photo: Getty)

Cerundolo commenced his campaign at the Rio Open with a 7-6 (9), 6-0 win over Hugo Gaston. He overcame a one-set deficit to hand Luciano Darderi a 6-7 (1), 6-3, 6-2 loss in the second round.

Muller knocked out home hope Fonseca in the first round, and upset eighth seed Tomas Martin Etchevery in the second round. He won both of his matches in straight sets. The Frenchman won his maiden title on the ATP Tour at the Hong Kong Open in the very first week of the new season.

Muller didn't win a match after that until this week. Cerundolo was the runner-up at last week's Argentina Open, and lost to Fonseca in the final. He has a pretty good record at the Rio Open, and made the semifinals in two of his previous three appearances here. He's now on the verge of reaching the last four yet again.

Cerundolo lost his prior and only encounter against Muller last year in Auckland, which was on hardcourts. Given the Argentine's current form and preference for clay, he will be the favorite to come through this clash.

Predicted winner: Francisco Cerundolo