Carlos Alcaraz suffered a shock defeat at the Cincinnati Open as Gael Monfils came from a set down to prevail from a rain-delayed encounter.

Monfils was 3-1 up in a second-set tie-break before rain stopped play on Thursday, but returned 24 hours later to win 4-6 7-6 (7-5) 6-4.

Once play resumed on Friday, Monfils continued where he left off but squandered three set points before eventually taking the tie this distance. 

Last year's runner-up Alcaraz struggled in the opening exchanges, with his French opponent finding a decisive break in the third game as Monfils took control of proceedings in Ohio. 

And Monfils' experience ultimately told, as the 37-year-old held out for the remainder of his service games to set up a meeting with Holger Rune in the last 16, condemning Alcaraz to a shock exit.

World number one Jannik Sinner, meanwhile, had no need to take to the court on his 23rd birthday, as he was handed a walkover following Jordan Thompson's withdrawal.

Data Debrief: The old head prevails

Monfils is the oldest player to defeat an opponent ranked in the ATP top-three since Jimmy Connors defeated Michael Stich in Memphis in 1992.

The world number 46 starred on serve, firing 15 aces throughout the contest compared to Alcaraz's seven, while also clawing back six of the seven break points he faced.