Jamaican Omar McLeod clocked the fastest time of the year to win the 110 meters hurdles at the Drake Relays in Iowa on Saturday as Olympic champion Aries Merritt finished fifth on his return from a kidney transplant.

Overcoming rainy conditions and a sodden track at the meeting in Des Moines, McLeod crossed the line first in a world-leading 13.08 seconds.

American David Oliver, who won gold in the 110-meter hurdles at the 2013 world championships, came in second (13.31) with London Olympic bronze medalist and Jamaican national record-holder Hansle Parchment third (13.42).

"This weather is atrocious, it really is," a beaming McLeod, 22, who won the men's 60 meters hurdles title at the world indoor championships in March, said in a trackside interview.

"I tried my hardest to get a good warmup and I started warming up real early . . . going up against guys like this, you have to be warm and you have to be ready. I am just glad I was able to come out here and finish it off, which was the plan."

World record holder Merritt, who was told he would never run again after being diagnosed with kidney disease in 2013, was delighted to finish fifth at his first track meeting since he received a new organ from his sister last September.

"My body felt really good," said Merritt, who won the bronze medal in the 110-meter hurdles at last year's world championships just four days before having his kidney transplant.

"I had some complications mid-race. I hit a hurdle and I almost wiped Oliver out. It was just a little bit of rust there but, as the season progresses, I will be sharper and sharper and I will be able to maintain. I had a good time out here."