Tyson Gay sent a message to missing rivals Usain Bolt and Asafa Powell with victory in the 100 metres at the London Diamond League meeting on Friday in a world leading time of 9.78 seconds.
The American, who beat Jamaican world record holder Bolt in Stockholm last week, defied the cold, damp evening conditions and, after a flying start, finished clear of the field. Jamaica's Yohan Blake finished second in 9.89.
Blake's compatriot Powell pulled out of the race on Thursday due to injury while triple Olympic champion Bolt announced this week he would not run again this season due to a back problem.
Gay also joined the ranks of the walking wounded and was limping after his impressive display, which was a fitting finale to the first day of the meeting that concludes on Saturday.
"I was hobbling a bit at the end -- my groin is a little sore but I'm sure it's okay," said the American, who had surgery on the area last year.
"I think there's more to come. It's great to be on top of the world, that's important to me," said Gay. "This is not the best shape I've ever been in because I'm still dealing with a few little injuries.
"My coach said that I can run 9.7 in any conditions and I think I showed that tonight."
American Bernard Lagat spoiled double European champion Mo Farah's homecoming in the 3,00 metres by pulling away from the Briton and Australia's Collis Birmingham on the final bend to clinch victory in seven minutes 40.36 seconds.
Farah, who won the European 5,000 and 10,000 titles last month, was roared on by a capacity crowd desperate to see him win but for once he had to settle for second in 7:40.75.
"My plan was just to hang back a little bit because I knew I hadn't raced in three weeks," said the 35-year-old Lagat.
"I wanted to see how I felt, and I felt good. Mo is a great athlete and I knew he was running strongly and I'm glad I was able to run with him really well today."
There was also disappointment for another crowd favourite, Phillips Idowu, who could only manage sixth in the triple jump with 16.54 metres.
"I was just tired today, running was good but I couldn't get my phases together," said the world and European champion.
"I'd have liked to put in a good performance for the home crowd, I would have loved to perform for them like in Barcelona (at the Europeans) so they could have seen me do my thing."
Sweden's former Olympic, world and European title holder Christian Olsson showed he was heading back to form after struggling with injuries for the past four seasons, winning the event with 17.41 ahead of France's Teddy Tamgho.
Canada's Priscilla Lopes-Schliep was not troubled by the poor conditions, beating favourite Lolo Jones in the 100 hurdles in the fastest time in the world this year of 12.52.
"My personal best is in the rain, so come rain or shine I know that I can perform... I just knew it was going to be a brilliant day," said the 27-year-old.
Australian Sally Pearson was second after a blistering start and Jones, also beaten by Lopes-Schliep in her heat, was third.
Olympic champion Steve Hooker and European gold medallist Renaud Lavillenie failed to clear their opening height of 5.51 metres in the pole vault competition, which had to be halted for several minutes because of a downpour.
Poland's Lukasz Michalski was the surprise winner, clearing 5.71.
"I can't really explain what went wrong," said France's Lavillenie after his first defeat of the season. "It was a bit cold and wet for me and I made some mistakes with my run-up."
Nadezhda Ostapchuk of Belarus maintained her dominance over Olympic and world champion Valerie Adams-Vili in the shot put this season with a best effort of 20.27.