Gilles Muller returns a forehand to Tommy Paul during their Atlanta Open quarter-final on Friday. Pic/Getty Images

Gilles Muller, coming off a Wimbledon quarter-final run and upset of Rafael Nadal, reached the ATP BB&T Open semi-finals by defeating US qualifier Tommy Paul 6-3, 6-1 on Friday.

The 34-year-old Luxembourg left-hander blasted 16 aces to oust the 20-year-old world number 291 in only 69 minutes to advance at the Atlanta hard court tune-up event for the US Open.