Borna Coric claimed an upset in the first round at the Western & Southern Open in Cincinnati, coming from a set down to defeat Benoit Paire in 1-6 6-3 6-4.
With the two players never facing each other before Sunday's match, the experienced Paire took the early ascendancy, winning 80 per cent of points on Coric's second serve to claim the first set with ease.
Despite being broken, 19-year-old Croatian Coric fought back to win the second set as Paire's serve faltered, with his first serve rate dropping to 37 per cent.
The world number 32 Frenchman's first serve rate dropped even further in the third to 26 per cent as he tallied nine double-faults in total, with Coric taking full advantage.
World number 51 Coric will face the winner of Nick Kyrgios and Lucas Pouille in the second round.