Stanislas Wawrinka was forced into three tie-breaks by teenager Chung Hyeon before eventually progressing to the third of the US Open in straight sets.

The reigning French Open champion and fifth seed is ranked 64 places above the 19-year-old South Korean, but was made to work very hard for his 7-6 (7-2) 7-6 (7-4) 7-6 (8-6) victory at Flushing Meadows.

Wawrinka's superior power and excellent serve proved to the difference between the two, the Swiss knocked down 26 aces and racked up 62 winners.

Next up for Wawrinka is Ruben Bemelmans after his opponent Jack Sock retired from their second-round match with heatstroke.

The world number five took control straight away as he broke for an early 3-0 lead. However, Chung soon produced a demonstration of his resiliency to level at 3-3 and then made Wawrinka save three break points to force a tie-break.

Chung had no answer for Wawrinka in the tie-break, but looked to be on course to level the match when he broke serve again to go 3-0 up in the second set.

However, Wawrinka responded as Chung paid for a sloppy service game at 2-4, surrendering the break and the initiative with an errant groundstroke.

Wawrinka once again had too much in the tie-break, which he clinched with an unreturnable serve.

Chung called for the trainer when 2-1 down in the third, but showed no signs of giving up and was able to save a match point at 6-5 down when Wawrinka fired a forehand long.

Wawrinka then saved a set point in the third tie-break of the contest before a fine forehand set up his second match point.

And this time he made no mistake, with victory wrapped up as Chung sliced a backhand volley wide.