US Open: What went wrong for ousted Wawrinka

Big-serving Canadian Milos Raonic halted former champion Stan Wawrinka's charge at the US Open on Friday, beating the Swiss wildcard 7-6(6), 6-4, 6-3 to book his berth in the last 16.

Wawrinka, making his first return to the site of his 2016 triumph since undergoing knee surgery, showed he was still shaking off the ring rust despite encouraging victories in the first two rounds.

The first set went down to the wire with nothing to choose between the two rivals, neither of whom were unduly troubled on serve.

Raonic lost the first three points of the tiebreak before recovering to level at 3-3 and showed great strength of character to save two set points before going on to claim the opener.

"It was tough," the Canadian said in an on-court interview.

"I was fortunate I got through that because I was falling behind in that tiebreak."

Wawrinka, who had won four of his five previous matches against Raonic, could not match his opponent's intensity in the final two sets and paid the price for some poor shot selection.

The 33-year-old is one of the best all-court players on the men's circuit and his one-handed backhand is matched only by that of his compatriot Roger Federer in terms of elegance.

It let him down repeatedly on Friday, though, as Raonic, sensing a weakness, targeted that side and duly prospered.

The Canadian serve-and-volley specialist made sure he stayed on the front foot throughout, firing down 14 aces to Wawrinka's four and coming to the net behind his booming serve 37 times with a success rate of 73 percent.

"I've got to just keep getting sharper," added Raonic, who is seeded 25th.

"I've got to find a way to get ahead a little earlier in the points and not get too defensive.

"If I can play on my terms I can compete against anybody."

Next up for the 27-year-old is a last-16 clash with American John Isner, the 11th seed, who beat Serbian Dusan Lajovic earlier in the day.