Jeremy Chardy dug deep to grind out a gruelling three-set win over John Isner and advance into the Rogers Cup semi-finals.

All three sets were determined via lengthy tie-breaks, with Chardy coming from behind to edge it 6-7(9) 7-6(13) 7-6(4) and settle a contest that spanned three-and-a-half hours in Montreal.

Nothing could separate the duo in a tight opening set that saw the first 12 games go with serve, but world number 12 Isner drew first blood to claim the opener after winning 11-9.

The American seemed to take a big step towards the last four when he broke his French counterpart in the third game of the second set en route to a 3-1 lead.

However, Chardy - ranked 49th in the world - broke back in the sixth game to level up the set as the pair then forced another tie-break, with the underdog winning this time with a gruelling 15-13 victory.

The nip-and-tuck nature resumed in the decider as both held their serve throughout regulation, but Isner's appetite for another lengthy tie-break waned as Chardy won 7-4 to clinch a last-four berth.