Stan Wawrinka continued his US Open journey, but Monday's fourth-round win over Donald Young was far from straightforward.

The fifth seed had to rediscover his best form after a second-set blip to triumph 6-4 1-6 6-3 6-4.

It was the first time the Swiss had dropped a set at this year's tournament, though his response was emphatic and he will await the winner of the match between Kevin Anderson and Andy Murray in the quarter-finals.

Young, by contrast, needed 14 sets to win his first three matches – seeds Gilles Simon and Viktor Troicki among his victims – and the world number 68 showed glimpses of his talent in a tight first set that was settled by a solitary break.

Wawrinka won 93 per cent of points on his first serve in the opener, but the second set was a different story as Young found another gear to win it in just 25 minutes.

He had joy targeting Wawrinka's usually lethal backhand and the French Open champion was being dominated from the baseline.

A double-break did the trick and Young served out on his second set point to level the match, with all the momentum apparently on his side.

Despite that, Wawrinka managed to seize the initiative back by racing into a 5-0 lead in the third set as Young's accuracy deserted him.

The American stopped the rot in game six, then broke and held again to keep Wawrinka, a semi-finalist at Flushing Meadows in 2013, on his toes.

It merely delayed the inevitable, though, as Wawrinka ultimately took a 2-1 lead with a love service game, following it up with a break at the start of the fourth.

Sensing victory was within his grasp, Wawrinka became even bolder with his shot selection and simply had too much for Young, whose challenge faded amid a valiant effort in the fourth set.