Japan Open 2025 Day 4: Men's singles predictions ft. Sebastian Korda vs Marcos Giron, Brandon Nakashima vs Jordan Thompson

First-round matches will continue on Day 4 (Thursday, September 25) of the Japan Open 2025. The third day of the tournament witnessed a couple of upsets. Eighth seed Frances Tiafoe blew a one-set lead during his opening-round showdown against Marton Fucsovics, going down 3-6, 6-1, 7-5.

Seventh seed Denis Shapovalov was also eliminated, losing 7-5, 6-3 to Daniel Altmaier. Former top 10 player Matteo Berrettini made a winning start to his campaign in Tokyo. He scored a comfortable 6-4, 6-2 win over Jaume Munar to reach the second round.

More players will aim to join him in the second round on Thursday. On that note, here are the predictions for some of the first-round matches lined up on Day 4 of the Japan Open 2025:

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#1. Sebastian Korda vs Marcos Giron

A runner-up finish in Adelaide and a quarterfinal showing at the Miami Open were Korda's best results during the early hardcourt swing. His results on clay in the lead-up to the French Open weren't impressive but he still managed to make the third round in Paris.

Korda was out for three months due to an injury following his exit from the French Open. He returned to the tour at the Winston-Salem Open and advanced to the semifinals. However, he withdrew prior to his match as his injury continued to bother him.

This affected his US Open campaign the following week, where he was forced to retire from his first-round match. He lost to Yibing Wu from a set up in the second round of last week's Hangzhou Open. He has a 15-12 record this year.

Giron enjoyed a decent level of success during the early hardcourt swing, reaching the fourth round of the Indian Wells Masters, the third round of the Australian Open, and three quarterfinals at lower-tier events. He failed to replicate these results on clay and grass, and his return to hardcourts was disappointing.

Giron snapped his five-match losing streak to reach the second round of the US Open, and made the last eight of last week's Chengdu Open. He has a 20-21 record for the season.

Korda is now trying to find his footing after his recurring injury niggles. While he won the pair's only prior meeting at the European Open 2022, Giron will be favored to win this contest on account of outperforming his compatriot this season and being injury-free.

Predicted winner: Marcos Giron

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#2. Ugo Humbert vs Jenson Brooksby

Ugo Humbert was the runner-up at the Japan Open 2024. (Photo: Getty)

A title in Marseille and a fourth-round appearance at the Australian Open stand out as Humbert's best results this year. He struggled on clay, and while he reached a couple of semifinals on grass, he eventually crashed out in the first round of Wimbledon. A similar fate awaited him at the US Open, where he fell at the first hurdle. His record for the season stands at 18-16.

Brooksby returned to the ATP Tour after a lengthy hiatus. It didn't take him too long to announce his arrival, capturing the title in Houston at the start of the clay swing. He also finished as the runner-up in Eastbourne. He reached the third round of the Cincinnati Open and then bowed out in the second round of the US Open. He has a 16-12 record this year.

This will be the third meeting between them. Humbert won their first encounter in straight sets at the Swiss Indoors 2022, while Brooksby needed three sets to triumph en route to the final in Eastbourne this year.

Humbert lost to compatriot Arthur Fils in last year's Japan Open final. While his current form makes another trip to the final a long shot, he will be favored to beat Brooksby at the very least. The American has a 2-6 record against top 50 players on hardcourts this year, making him the underdog in this duel.

Predicted winner: Ugo Humbert

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#3. Brandon Nakashima vs Jordan Thompson

Nakashima has a 28-23 record this season. He has reached three semifinals, all at the ATP 500 and ATP 250 level. He recently made the last four at last week's Chengdu Open, going down to eventual champion Alejandro Tabilo. He took part in the Japan Open last year as well and lost to Humbert in the second round.

Thompson has a 12-14 record this year, with a fourth-round finish at Wimbledon being the highlight. He also reached the third round of the Miami Open. He has arrived at the Japan Open on a three-match losing streak. He also competed in Chengdu last week and lost to Tabilo in the first round.

The two are familiar rivals, having faced off six times prior to this. Their seventh meeting was a bust, with Thompson withdrawing prior to their match at the Italian Open 2025.

Nakashima leads their rivalry 4-2 and won their previous meeting at Wimbledon 2024 in straight sets. He also leads 3-1 on hardcourts, thus further tilting this contest in his favor. The American also has more than twice as many wins as Thompson this year, making him a safe bet to win this match.

Predicted winner: Brandon Nakashima

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#4. Alex Michelsen vs Ethan Quinn

Alex Michelsen at the US Open 2025. (Photo: Getty)

Michelsen shot to limelight with his run at the Australian Open, reaching the fourth round of a Major for the first time. He also progressed to his maiden Masters 1000 quarterfinal at the Canadian Open a few weeks ago. He has peaked at No. 32 in the ranking so far but finds himself in a slump. He will aim to snap his three-match losing skid with a win at the Japan Open.

Quinn beat Yuta Shimizu and Mattia Bellucci to book his spot in the main draw of the Japan Open. In his first full year on the ATP Tour, he has risen from No. 199 to No. 81 in the rankings. However, his progress has stalled in recent weeks, having lost his last three main draw matches.

Both players are 21 years of age. However, Michelsen has progressed at a much faster rate compared to his peer. He has 22 wins this year, while Quinn has tallied 11 wins on the main tour. Michelsen's experience should help him sneak past his compatriot in a must-win match for both players.

Predicted winner: Alex Michelsen