Tsitsipas stunned in US Open first round, Medvedev and Murray safely through

Stefanos Tsitsipas was stunned in the first round of the US Open on Monday after the fourth seed lost to Colombian qualifier Daniel Galan 6-0 6-1 3-6 7-5.

Tsitsipas, 24, was one of five players who could have ended the season's fourth and final Grand Slam as the men's world No 1 but he appeared hampered by an arm injury against Galan, who won the first 11 games and held off an apparent fightback to seal victory on his ninth match point.

Tsitsipas had a physio tend to his right arm before the sixth game in the second set, when he finally got on the board, and again during the break before the third set, when he broke Galan in the second game.

The Greek, who has never got past the third round in New York and had hoped to do better this year after reaching the Cincinnati final, dropped only four of his first-serve points in the third set and looked as though he had the momentum when he broke Galan again in the opening game of the fourth set.

But the Colombian world No 94, playing in the main draw for the first time, never lost his composure, sending across 41 winners throughout the match and refusing to give into his heavily favoured opponent.

"I just stayed calm. I lost the (third) set but I felt I was doing better and better," said Galan.

Dripping with sweat and with the crowd inside Louis Armstrong Stadium egging them on, Galan nearly broke Tsitsipas for the match five times in the 10th game of the fourth set, and finally got the job done in the 12th, gazing at the stands with disbelief.

"I can't explain how I feel right now," he said after the match. "I went through the match well."

Galan next faces Jordan Thompson in the second round after the Australian fought back from two sets down to defeat Italy's Lorenzo Sonego