NEW YORK: Top seed and five-time champion Roger Federer withstood an inspired challenge from Simon Greul before defeating the pesky journeyman 6-3, 7-5, 7-5 in the second round of the US Open on Wednesday.

The 28-year-old Greul squandered two set points in the second set and a 3-0 lead in the third, eventually succumbing to Federer's punishing groundstrokes.

"I just had to make him play more shots, be more tough," said Federer. "I had to raise my level today to win because that's what was required to get through."