Madison Keys advanced to the French Open semi-finals with a hard-fought 7-6 (7-5) 6-4 victory over Yulia Putintseva on Tuesday.

Runner-up at last year's US Open, Keys is enjoying her best run at Roland Garros and up next for the 13th seed is a final-four meeting against Daria Kasatkina or Sloane Stephens, to whom she lost in the Flushing Meadows decider.

Keys is yet to drop a set at this year's tournament, although that record looked in danger on Court Suzanne Lenglen when Putintseva was serving for the lead at 5-4 in the first.

The American responded precisely when she needed to, however, and overcame the disappointment of seeing three set points come and go to get her nose in front.

The crucial break in the second arrived in game seven and Putintseva, the only unseeded player left in the women's draw, bowed out at the last-eight stage, as she did to Serena Williams in 2016.

After a tightly-contested opening six games, Keys was the first to blink as Putintseva secured a break, a deft drop-shot forcing her opponent long before the American netted.

Putintseva fell 15-40 down in serving for the set, however, Keys chasing down another drop-shot to this time fire in a winner, followed by a thumping forehand down the line to get back on serve.

Two set points slipped away for Keys at 6-5 as Putintseva forced a tie-break, where the American's rasping forehand return earned two more opportunities. 

The first was rescued by Putintseva's lucky net cord but the second was converted with a backhand into the open court.

World number 98 Putintseva was irked by a call going against her early in the second set and her mood was hardly improved when Keys took control with a break for 4-3.

Unlike Putintseva in the first, the American had few problems in serving out the set and the match, as she celebrated a third appearance in the last four of a grand slam.

STATISTICAL BREAKDOWN
Keys [13] bt Putintseva 7-6 (7-5) 6-4

WINNERS/UNFORCED ERRORS
Keys - 30/21
Putintseva - 12/10

ACES/DOUBLE FAULTS
Keys - 3/0
Putintseva - 0/1

BREAK POINTS WON
Keys - 2/4
Putintseva - 1/1

FIRST SERVE PERCENTAGE
Keys - 57
Putintseva - 78

PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Keys - 83/55
Putintseva - 66/64

TOTAL POINTS
Keys - 68
Putintseva - 61