Learner Tien is the only remaining seed in a wide-open top quarter of the Montreal draw, and he will run into Thiago Agustin Tirante on Sunday. Another fourth-round matchup pits Daniel Merida against Tallon Griekspoor.
(12) Learner Tien vs. Thiago Agustin Tirante
Tien did not exactly arrive at the National Bank Open with a ton of momentum. The 19th-ranked American struggled physically in a Wimbledon second-round loss to Marton Fucsovics and then lost right away in Washington, D.C. to Adrian Mannarino. Suddenly, though, Tien — in part thanks to a depleted draw — is looking like a real title contender in Montreal. He opened with a 6-3, 0-6, 6-3 victory over Gael Monfils and then destroyed Tommy Paul on Friday night.
Up next for the left-hander is a fourth-round showdown against Tirante on Sunday. The 65th-ranked Argentine continues to show that he is not one-surface player, booking his spot in the last 16 with wins over Duncan Chan, Taylor Fritz, and Alexei Popyrin. Still, it goes without saying that Tirante would much rather contest this particular matchup on clay. Count on Tien having too much consistency and guile for Tirante’s firepower.
Pick: Tien in 2
Tallon Griekspoor vs. Daniel Merida
If you had been told at the start of the year that Merida would be ranked ahead of Griekspoor at the Montreal Masters, it would have been hard to believe. Alas, that is the reality of the situation — albeit by a modest six spots (63rd to 69th). Whereas it has been a rough season for Griekspoor, Merida has earned all 15 of his ATP-level match victories in his career during this 2026 campaign.
Grieskspoor, though, appears to be turning it all around north of the border. The Dutchman dismissed Lorenzo Sonego 7-6(5), 7-5, upset No. 1 seed Alexander Zverev 6-7(3), 6-2, 6-4, and then ousted Matteo Arnaldi 3-6, 6-4, 6-3. Merida has advanced by taking out Liam Draxl, Ugo Humbert, and Alex Michelsen — requiring three sets against Draxl and Michelsen. This should be a close one, with slight edges in the surface and experience going to Griekspoor.
Pick: Griekspoor in 3
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Tien in 3, 6-3, 3-6, 6-4.
Greek in 2
The youngsters are having a great tournament. Tien back to his best and look at Merida finding his gears against the more experienced player! We’re in for an interesting US Open.