Jannik Sinner dropped a set at an ATP Masters event for the first time in 186 days but he still managed to book a spot in the Monte Carlo quarter-finals with victory over Tomas Machac.
The Italian has lifted the past three Masters 1000 titles – at Paris, Indian Wells and Miami – without conceding a set.
However, his streak of 37 consecutive sets was suddenly snapped when he lost control in the second set and Czech Machac took advantage to win the tie-break.
It was the first time Sinner had dropped a set at that level since October’s Shangai Masters, when he retired injured against Netherlands’ Tallon Griekspoor.
But Sinner regained his composure in Monaco to see out the decider and complete a 6-1 6-7 (3-7) 6-3 victory- his 19th in a row at a Masters tournament.
The second seed, who has never won a clay-court Masters 1000 title, will face Canadian sixth seed Felix Auger-Aliassime in the last eight.
If Sinner wins the Monte Carlo tournament he will replace Carlos Alcaraz as the world number one when the rankings are updated on Monday.
He has no ranking points to defend until the Italian Open at the start of May because he was serving a three-month suspension this time last year for failing two doping tests.