Spaniard Rafael Nadal was a point away from defeat against big-serving Kevin Anderson, but came alive late in the second set to score a 4-6, 7-6 (8-6), 6-2 victory in Paris Masters to secure a quarter-final berth.
The seventh-seeded Nadal had won two previous matches against Anderson in straight sets, but he struggled against the South African's big serve in the fast indoor conditions and found himself down a match point in the second-set tiebreaker on Friday, reports Efe.
The 29-year-old Spaniard, who has admitted to lacking confidence earlier in the year, showed the mental strides he has made in recent weeks by claiming that must-win point when serving down 5-6 in the tiebreaker and then tying the match at a set apiece two points later.
The 14-time Grand Slam champion found himself against the ropes early on when he lost serve in the third game of the match.
That break was costly against Anderson, who hit eight aces and did not drop his serve once en route to capturing the first set.
The South African then was even more dominant on his service games in the second set, although Nadal stayed firm on his own serve and eked out the tiebreaker to force the decider.
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The contest then began slipping away from the 11th-seeded South African when he lost his serve in the opening game of the third set; he had one last chance to get back in the match but squandered six break-point chances in the 12-minute fourth game.
The Spaniard then got an insurance break to go up 5-2 and served out the victory.
Anderson put just 50 percent of his first serves in play and struck only two aces - out of 20 total - in the third set.
Nadal, who reached the final of this event in 2007, will next take on fourth-seeded Swiss Stanislas Wawrinka, a 6-4, 7-5 winner over Serbia's Viktor Troicki, in Friday's last quarter-final.