US Open: Milos Raonic cramps up in shock exit while Rafael Nadal makes history as $150m new roof makes debut

Wimbledon finalist Raonic eliminated by qualifier Ryan Harrison but Nadal cruises into third round despite brief rain delay

Milos Raonic suffered a shock defeat to US Open qualifier Ryan Harrison (Getty)

Wimbledon finalist Milos Raonic admits he fell victim to cramp and nerves after he endured a shock defeat to qualifier Ryan Harrison at the US Open.

America's Harrison is ranked 120th in the world but he took full advantage of his opponent's discomfort to win 6-7 (4/7), 7-5, 7-5, 6-1.

Raonic, seeded fifth, had been among the favourites to be crowned champion at Flushing Meadows, after an excellent season that has included reaching the semi-final at the Australian Open and the final at Wimbledon.

The Canadian, however, was hamstrung by cramp, which he said was brought on by anxiety, and it was Harrison who booked his place in round three.

"It was probably just nerves and stress, a mental sort of over-exuberance," Raonic said.

"Cramping in the left arm, right forearm there towards the end of the third set, both quads, a little bit in the hip flexor on the left. It was just catching me all over."

Raonic added: "I couldn't switch grips from one point to the next. There were a few points where I would hold the racquet with my left hand and trying to stretch out my right hand in between shots, and that's not going to work."

Harrison roars with delight after beating Raonic (Getty)

Raonic becomes the biggest casualty of the US Open so far but it could prove a breakthrough win for Harrison, who was once considered a rising star of American tennis.

Dropping to 197th in the world in 2014, the 24-year-old said a crisis meeting with his parents earlier this year has helped to turn the tide.

"I met with my family. I met with my dad, my fiancee, people close to me," Harrison said.

"I talked to them just about starting to develop a series of matches in a row where emotionally I was able to be selective about when I was getting excited.

"If I did get irritated, it wasn't at the wrong times and it wasn't taking me out of the match. It was just a decision to be resilient out there in the moment."

Rafael Nadal had no problems in beating Andreas Seppi to reach the third round (Getty)

Novak Djokovic stands to benefit from Raonic's exit given they were due to meet in the semi-finals and the Serbian enjoyed a far easier passage, after Jiri Vesely withdrew with a left forearm injury.

The walkover comes as a timely boost for Djokovic, who has been struggling with injury himself and he now has an extra day to recover before facing Russian Mikhail Youzhny on Friday.

"I'm very, very disappointed right now," Vesely said. "Playing Novak, you have to be 100 per cent ready."

Elsewhere, fifth seed Marin Cilic won through to the third round along with French pair Gael Monfils and Jo-Wilfried Tsonga.

The Arthur Ashe Stadium roof was closed for the first time (Getty)

In the last match of the night session, Rafael Nadal coasted past Italian Andreas Seppi 6-0, 7-5, 6-1.

The one-sided contest was perhaps most memorable for the first closing of the new US dollars 150million roof in Arthur Ashe Stadium, after rain began to fall during the second set.

The suspension of play lasted only seven minutes and 22 seconds and Nadal hit the first competitive ball with the construction closed. The Spaniard was also first to practice under the roof last week.

"It is great," Nadal said. "It's an unbelievable, unbelievable court."

PA