Australian Open champion Stanislas Wawrinka powered into the quarter-finals of the US Open on Monday with a 7-5, 4-6, 7-6 (9/7), 6-2 victory over Tommy Robredo. (Read: Djokovic, Murray Book Quarter-Final Showdown)
The third-seeded Swiss fired 18 aces, saving two set points in the third-set tiebreaker and dominating the fourth set against the 16th-seeded Spaniard.
Wawrinka fired 75 winners, including 27 in the third set that surpassed Robredo's total of 19 for the match. (Bouchard Knocked Out, Serena Storms Into Quarters)
"It was a really tough battle today," said Wawrinka, who also survived a tumble into the courtside seats in Armstrong Stadium when he hit the knee-high board surrounding the court at full stretch for a shot.
"I had some ups and downs physically," he said. "From that I'm OK, I'm more tired from the running, from the match.
"When you win, it's always more easy to feel good after," added Wawrinka, who had won only two of his prior eight matches against Robredo.
One of those victories was in the fourth round of the Australian Open en route to his first Grand Slam title.
He will face either fifth-seeded Canadian Milos Raonic or 10th seeded Kei Nishikori of Japan for a place in the semi-finals.