NEW YORK (Reuters) - Milos Raonic became the first major casualty of the US Open when American qualifier Ryan Harrison shocked the Canadian fifth seed 6-7 (4-7), 7-5, 7-5, 6-1 on Wednesday to reach the third round of the year's final grand slam tournament.
Raonic, who last month became the first Canadian man to reach the Wimbledon final, arrived at Flushing Meadows looking to take the next big step in his career but his bid was cut short by the 120th-ranked Harrison.
The 24-year-old American, who had beaten Raonic once in their previous two meetings, came prepared to give the sixth-ranked Canadian a battle and proved the more durable during in a 3hr 37min match played in sweltering conditions.
"The first two sets today were well over two hours, it was extremely physical," said Harrison. "When you have the crowd behind me like today you don't even realise how physical it is out there, you're just playing on adrenaline."
While Harrison remained cool and collected it was Raonic, 25, who wilted and called for the trainers several times to deal with cramps and a troublesome left wrist.
Harrison, who advanced to the third round of a grand slam for the first time, will next meet Cypriot Marcos Baghdatis, a 6-2, 6-4, 3-6, 6-4 winner over Frenchman Benoit Paire.
"This is a tournament that you just dream of growing up," said Harrison. "The coolest thing for me this year is that me and my brother are both playing in the main draw.
"As kids growing up, playing each other you always dream of playing in the Open and we both got to do it this year. I hope to keep it going."
Raonic's physical problems were evident in the third set, and he took a medical time-out while leading 2-1 with a wrist issue and later had massages for cramping.
Sensing his opponents distress, Harrison moved in with the knockout punch by breaking again to take the third and Raonic had no answers as the American steamrolled through the fourth.
"Halfway through the second set," said Raonic when asked when cramping became an issue. "I can't remember a single time where I've lost a match because of cramping.
"But I didn't serve well to start this tournament. That's normally my go-to. That can keep me out of situations. I think that sort of added a little bit more than I normally have to deal with."