Jannik Sinner advanced to the Miami Open quarterfinals on Tuesday with a straight-sets victory over unseeded American Alex Michelsen, keeping his bid for the "Sunshine Double" alive.
The Italian second seed, seeking to add Miami to his recent Indian Wells triumph, claimed a 7-5, 7-6 (7-4) win in 1 hour, 41 minutes.
Four-time Grand Slam finalist Sinner will meet 19th seed Frances Tiafoe in the last eight after being pushed by 40th-ranked Michelsen.
After a cautious start, Sinner turned up the pressure in the ninth game of the first set, creating three break points. Michelsen held firm, but Sinner finally secured the break in the 11th game and served out to take the opening set.
Michelsen hit back in the second set, breaking Sinner for a 4-2 lead before holding to go up 5-2.
Michelsen appeared to struggle with the bright late-afternoon sunlight on Hard Rock Stadium's main court, and Sinner came roaring back to force a tiebreak.
Sinner sealed the win with a thumping serve that Michelsen could only return wide.
"I feel like I served very well in important moments, and that helped me out, especially in the tough moments," Sinner said, unfurling 15 aces to Michelsen's three.
"But today was not easy. I played a night match yesterday and today in the daytime, so the conditions were very different."
Home favorite Tiafoe advanced to his quarterfinal date with Sinner after battling past France's Terence Atmane 6-4, 1-6, 6-4.
Spanish qualifier Martin Landaluce, ranked 151st in the world, upset American 32nd seed Sebastian Korda, 2-6, 7-6 (8-6), 6-4.
The win marked another impressive result for the 20-year-old Landaluce, who eliminated Russian 14th seed Karen Khachanov earlier in the tournament.
Korda, who had beaten world No. 1 Carlos Alcaraz in the previous round, held a match point late in the second set, but Landaluce survived to set up a quarterfinal against Czech 21st seed Jiri Lehecka.
Landaluce, who had failed to register a single win at tour level in 2026 before arriving in Miami, dedicated his latest success to his late grandmother.
"She would have been 101 last week, and she passed away a few months ago. I wanted to give her the victory," Landaluce said.
Lehecka booked his place in the quarterfinals by ousting sixth seed Taylor Fritz 6-4, 6-7 (4-7), 6-2 in 2 hours, 25 minutes.
"I just felt that in the third set, if I wanted to beat a guy like Taylor, I just needed to go for it and be aggressive," Lehecka said.
American 22nd seed Tommy Paul set up a quarterfinal against France's Arthur Fils after cruising past Argentina's Tomas Etcheverry 6-1, 6-3.
Fils beat Monaco's Valentin Vacherot 6-4, 6-7 (4-7), 6-4.
Argentina's 18th seed Francisco Cerundolo followed up his upset of Daniil Medvedev on Monday with a 6-4, 6-3 defeat of French 31st seed Ugo Humbert.
Cerundolo will face Alexander Zverev in the last eight after the German third seed defeated France's Quentin Halys 7-6 (7-4), 7-6 (7-1).
