(REUTERS) - Big-serving South African Kevin Anderson squandered two match points before finally overcoming Austrian top seed Dominic Thiem in a compelling three-set slugfest at the Washington Open on Thursday.

The clock had almost struck midnight when the 15th seed finally closed out the third-round match with his 21st ace to seal a 6-3, 6-7 (6-8), 7-6 (9-7) victory in a little under three hours.

In a high-quality contest, 45th-ranked Anderson seemed to have frittered away his chances when he wasted a first match point in the second set, but regrouped mentally and even survived a match point against him in the deciding tiebreak.

Anderson's power game is ideally suited to the super-slick centre court surface at Rock Creek Park that has officially been measured as faster than Wimbledon and the Australian Open.

Thiem staved off defeat the first time after an 11-stroke rally culminated with a whipped forehand winner into the corner that Anderson could only watch helplessly as it whistled past.

The world No. 7 then captured the next two points of the tiebreak to level the score at one set apiece and send the contest into an exciting decider.

"I felt I had it in the second set, but I tried to stay as positive as possible," 31-year-old Anderson told Tennis Channel.

"I was down two breaks in the third but kept fighting and managed to play some of my better tennis."

In quieter surroundings on an outside court, Indian world No. 200 Yuki Bhambri continued his dream run.

After taking out defending champion Gael Monfils of France in the second round, Bhambri produced a successful encore to beat Argentinian Guido Pella 6-7 (5-7), 6-3, 6-1 and set up a quarter-final encounter with Anderson.