Félix Auger-Aliassime reaches US Open semi-finals after Carlos Alcaraz retires

• Auger-Aliassime advances after Alcaraz retires trailing 6-3, 3-1
• FAA reaches semi-final after Alcaraz retires - as it happened
• Giantkiller Fernandez topples Svitolina to reach semi-finals

What had started as one of the more intriguing US Open quarter-finals in years between a couple of the tour's most promising young guns ended prematurely Tuesday night as Felix Auger-Aliassime abruptly went through to the last four at Flushing Meadows when the Spanish teenager Carlos Alcaraz retired down a set and a break after only 68 minutes.

The 12th-seeded Montrealer nicknamed FAA was leading 6-3, 3-1 before a nearly packed house at Arthur Ashe Stadium when Alcaraz called a halt to the proceedings following a visit from the trainer during the previous change of ends. It was not immediately clear why the 55th-ranked Alcaraz retired from the match, neither to Auger-Aliassime nor the roughly 20,000 spectators on hand, though he told reporters afterwards it was down to a problem in his upper right thigh.