Karsten Warholm, the Olympic champion and world-record holder in the 400m hurdles, pulled up injured on his return to competition at the Diamond League meet in Rabat on Sunday, just weeks before the Norwegian star defends his world title.

After a blistering start out of the blocks, Warholm abruptedly stopped after clipping the first hurdle, clutching the back of his right thigh.

By the time the rest of the field had finished the 26-year-old had placed ice on his right leg as coach Leif Olav Alnes looked on.

"I am very disappointed for this injury. I think it's a hamstring tear, I will focus on treating it and come back stronger. I also feel sorry for the crowd," said Warholm.

There are less than six weeks left for the two-time defending world champion to recover before the world championships in Eugene, Oregon from July 14-25.

American Khallifah Rosser went on to win the 400m hurdles in 48.25 seconds.

Earlier, Olympic champion Elaine Thompson-Herah eased to victory in the women's 100m.

The 29-year-old clocked 10.83sec to remain unbeaten this season, finishing ahead of Ivorian Marie-Jose Ta Lou in 11.04 and fellow Jamaican Natasha Morrison, 11.22.

Thompson-Herah, a triple Olympic gold medallist in Tokyo over the 100m, 200m and 4x100m relay, could not improve on her season best 10.79sec achieved in Eugene a week ago.

"I feel amazing about the race today," said the Jamaican.

"This is my third time in Rabat and I'm super excited about the new meeting record of 10.83. For the next event in Rome, I'm following the same process and keeping up the same pace."

Morocco's Soufiane El Bakkali gave the home crowd a boost with a blistering performance on his way to victory in the 3,000m steeplechase, the final race of the evening.

The Olympic champion offered a new high-flying duel against his runner-up from Tokyo, the Ethiopian Lamecha Girma.

Stalled behind Girma, the Moroccan pulled ahead on the last lap and took advantage of the pace set by his rival to achieve a very fast time of 7min 58.28sec.

El Bakkali snatched the best performance in the world this season from Girma, who had just managed 7min 58.68 sec on Tuesday in Ostrava, and finished Sunday's race in less than eight minutes (7:59.24).

Since 2015, only these two athletes have descended under eight minutes in the event.

Sunday's race also marked the return to the top of the Kenyan reigning double world champion Conseslus Kipruto, who finished fourth in 8min 12.47sec.