Stefanos Tsitsipas declared he was “speechless” after his stunning victory against Arthur Fils in the first round of the 2026 US Open.

The world No 53 downed No 10 seed Fils 4-6, 7-6(3), 6-1, 6-4 in Louis Armstrong Stadium on Monday at Flushing Meadows.

Tsitsipas was on the brink of falling two-sets-to-love behind when he trailed 4-6, 2-5, but he rallied to win the second set on a tiebreak before sealing a decisive triumph.

The 28-year-old Greek is a two-time Grand Slam finalist and former world No 3, but he was the clear underdog heading into this match.

Fils arrived at the US Open at his career-high ranking of world No 11 after winning the biggest title of his career at the Cincinnati Masters.

The 22-year-old Frenchman was seen as a genuine title contender by many analysts, but Tsitsipas produced the biggest upset of the tournament so far.

In his on-court interview, Tsitsipas said: “I’m speechless. I don’t know what to say. It’s an amazing start to the tournament. Guys, you had my back the entire match. Thank you so much.”

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Asked what he told himself when he was down a set and a break, Tsitsipas said: “Let go of expectations. I feel like we can get dragged with a lot of expectations.

“Carrying that heavy boat is not easy during a match, especially when the psychological game of a match like that is crucial. It’s important to stay well composed and keep building on your game.

“I owe everything to letting go, not having any expectations, and just being a warrior, a Greek fighter. All the above.”

Asked if he can get back to the very top of the game, Tsitsipas replied: “Why not? I’m taking it a day at a time. I don’t wanna be looking too far away. I prefer to stay grounded in the moment.

“A win like this today matters a lot to me. I’m very proud of myself. The way I fought and executed my game plan.

“Most of all, I have an incredible team by my side that was just dragging me through the entire process. I can’t be more happy right now.”

Tsitsipas will play world No 139 Lloyd Harris in the second round.