The 18-year-old Scot, who has shot into the top 100 after starting the year ranked 411, defeated the American third seed to enter the semi-final of the Thailand Open.
Mahesh Bhupathi and Justin Gimelstob edged out Robby Ginepri and Gilles Muller in the first round of the Thailand Open
Andre Agassi served up his traditional late-night feast at the U.S. Open on Monday, beating fellow American Robby Ginepri to move into the second round.
The top seed won two matches on Thursday to advance to the last eight at the RCA Tennis Championships in Indianapolis.
The top seed was leading 6-4, 2-5 against Michel Kratochvil before heavy rain suspended play at the RCA Tennis Championships.
The US Open champion gave the US a 2-0 lead over Austria on the opening day of their first-round Davis Cup World Group tie.
Venus Williams unleashed the fastest serve by a woman at a grand slam as the American kept the Stars and Stripes fluttering at the French Open on Wednesday.