Milos Raonic and Stan Wawrinka stunned in first-round defeats at Queen's

Wawrinka was beaten at Queen's 7-6 (7/4), 7-5 by Feliciano Lopez shortly after Raonic endured a 7-6 (7/5), 7-6 (10/8) defeat to Australian wild card Thanasi Kokkinakis

Milos Raonic was runner-up at Queen's in 2016 (Getty)

Milos Raonic and Stan Wawrinka both made losing starts to their grass-court seasons on Tuesday by crashing out in the Aegon Championships first round.

Wawrinka, who reached the French Open final earlier this month, was beaten at Queen's 7-6 (7/4), 7-5 by Feliciano Lopez shortly after Raonic endured a 7-6 (7/5), 7-6 (10/8) defeat to Australian wild card Thanasi Kokkinakis.

Kokkinakis' victory was perhaps the more surprising given it was the 21-year-old's first ever against an opponent ranked inside the top 10 and came in only his fifth match this year, following a long lay-off with a shoulder injury.

Raonic was a runner-up both here and at Wimbledon in 2016, losing on each occasion to Andy Murray, and the world No 6 considered a genuine contender again at the All England Club next month.

But he too has struggled with a hamstring problem this season and the Canadian insists his confidence remains intact ahead of the third grand slam event of the year.

"Obviously the disappointment is high right now but whatever the result was this week, I don't think that's really going to change my chances," Raonic said.

"I believe I can play really well. Honestly, if this was three out of five (sets) today, it's a scenario I feel even more comfortable in because I really do believe a lot of my game can give me more time to figure out the situation and deal with it a little bit better.

This was Kokkinakis' first victory against an opponent ranked inside the top 10 (Getty)

"But it's not. So I will go into Wimbledon with a lot of confidence because I have prepared really well."

Unlike Raonic, Wawrinka has never viewed grass as his favourite surface and the world No 3’s discomfort was evident again on Centre Court.

Lopez looked more honed, having found rhythm in five grass-court matches last week en route to the final in Stuttgart while Wawrinka was playing his first of the summer.

"He's playing with confidence from last week, making the final," Wawrinka said.

"Today was a tough match. I'm really sad to have lost it. I think in general for a first match on grass, the game wasn't that bad. I was serving quite well.

Wawrinka has never viewed grass as his favourite (Getty)

"But again, there is still a lot of work to do physically and on my tennis, on my game, to be in a better place on grass."

Wawrinka also reported some pain in his left knee since switching from the clay at the French Open but indicated that it was not a major problem.

"I was feeling good after Paris. Tired, especially mentally also," Wawrinka said.

"But since two days I had some knee pain because of the change of the surface.

Lopez played in five grass-court matches last week (Getty)

"When you arrive on grass, you need to be careful. I need to be careful to make sure it doesn't bother me too long."

On a day of shocks in south west London, Andy Murray later lost to Australian lucky loser Jordan Thompson, who only came into the draw after Aljaz Bedene withdrew.

Bedene, who is the British number four, pulled out with a wrist injury on Tuesday morning and now faces a race against time to be fit for Wimbledon, starting on July 3.

"I'm still confident I will be able to play. Maybe I won't be 100 per cent," Bedene said.

"I had problems in the French Open. It didn't get any better so yesterday (Monday) I had an MRI scan, which shows an injury on the right wrist."

Britain's Cameron Norrie also departed after the 21-year-old was beaten 6-1, 6-4 by American Sam Querrey.

James Ward, another Briton, was beaten 6-2, 6-2 by France's Julien Benneteau.