PARIS (Reuters) - World number three Dominic Thiem survived a third-set wobble to beat American qualifier Jack Sock 6-1 6-3 7-6(8) on Wednesday and book his French Open third-round spot.
U.S. Open winner Thiem needed just 25 minutes to break 28-year-old Sock, a former top 10 player, three times and storm through the first set.
The Austrian third seed, beaten by 19-times Grand Slam champion Rafael Nadal in the last two Roland Garros finals, was brimming with confidence on his favourite clay surface after winning his first Grand Slam title at this month's U.S. Open.
"I'm very happy," Thiem said in an on-court interview. "I messed it up a bit in the third set, up 4-3 and 40-15."
"I found myself in the tiebreak and he played very well, particularly in the second and third sets. I was lucky to save the three set points in the tiebreak."
Sock, whose injury-hit 2019 saw him tumble down the rankings to his current 310th, tried to mix it up in the second set, hitting several superb drop shots.
But he was ultimately helpless against Thiem's baseline power and superior fitness.
Thiem, however, lost his focus in the third set and was broken twice, making more than twice as many unforced errors than in the two previous sets combined to allow Sock two breaks to lead 5-4 and 6-5.
The Austrian, trailing 6-3 in the tiebreak, then saved three set points before sealing victory at the first opportunity.
Thiem will next play the winner of the match between in-form Norwegian Casper Ruud, a semi-finalist in Rome this month, and American Tommy Paul.
(Reporting by Karolos Grohmann,; Editing by Christian Radnedge and Ed Osmond)