Coco Gauff came through a three-hour battle with Ukraine’s Marta Kostyuk to reach the semi-finals of the Australian Open for the first time.

The US Open champion had cruised through to the last eight but was pushed very hard by first-time grand slam quarter-finalist Kostyuk before clinching a 7-6 (6) 6-7 (3) 6-2 victory after three hours and eight minutes.

Gauff trailed 5-1 in the opening set before fighting back to win it, saving two set points.

She served for the match at 5-3 in the second set but now it was Kostyuk’s turn to surge back, and it was not until the third set that Gauff took control of the match, opening up a 5-0 lead.

The 19-year-old is the youngest American to reach the women’s semi-finals in Melbourne since Mary Joe Fernandez back in 1991, and she is now two wins away from making it back-to-back slam titles.

If she is to achieve that, she will surely need to play at a consistently higher level than here, with the pair making a combined 107 unforced errors.