Jannik Sinner crashed out of the Qatar Open quarter-finals in a shock 6-7 6-2 3-6 defeat to World No 16 Jakub Mensik.
After a back-and-forth first set went the way of Mensik, Sinner showed characteristic poise to win four straight games in a dominant second set showing that seemed to take the game back under the control of the Italian.
But the Czech No 1 caught Sinner off guard in the decider, breaking in the opening game, and broke once more at 5-3 to win the game against the serve to secure a brilliant victory.
Mensik will face Frenchman Arthur Fils in the semi-final as he looks to win his third singles title.
Carlos Alcaraz came back to beat Karen Khachanov 6-7 6-4 6-3 to reach the Qatar Open semi-final in a high quality match lasting almost three hours.
Khachanov made it difficult for the World No 1 after a brilliant tie-break performance saw him take an hour-long first set, but the Spaniard roared back in the next two sets with some fantastic tennis to win the next two sets and secure his semi-final place, in front of former Man Utd coach Ruben Amorim in the stands.
The Australian Open champion wins his 28th consecutive match on an outdoor hard court, and sets up a tie with defending Qatar Open champion Andrey Rublev in the semi-final.
Coco Gauff hit form to reach the semi-finals of the Dubai Championships.
The third seed has struggled with her game but dominated against crowd favourite Alexandra Eala from the Philippines, winning 6-0 6-2.
Gauff will next bid for revenge against Elina Svitolina, who she lost to heavily in the Australian Open quarter-finals, after the Ukrainian ended the run of lucky loser Antonia Ruzic with a 3-6 6-2 6-3 victory.
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