Tyson Gay ran a world leading 9.77 seconds to win the 100 metres at Rome's Golden Gala on Friday and show Olympic champion Usain Bolt that he will not surrender his world sprint titles without a fight next month.
The American had to be in good form to see off Bolt's Jamaican compatriot and former 100m world record holder Asafa Powell, who ran 9.88 despite saying beforehand was not fully fit after suffering an ankle injury over two months ago.
Another Jamaican, Yohan Blake, came third with a time of 9.96 in the second attempt at the race after Daniel Bailey of Antigua false started.
Bolt is favourite to steal Gay's 100m and 200m crowns at the world championships in Berlin after winning the Olympic titles in both events in Beijing last year with world record times of 9.69 and 19.30 respectively.
But Gay's current form suggests he may give Bolt a run for his money after the American's Olympic campaign was hampered by a hamstring injury.
Friday's win comes after he ran a wind-assisted 9.75 seconds in the 100m at the US world championship trials last month and 19.58 in the 200m in May in New York, the third fastest ever.
"I've been learning how to refocus at the start [after false starts] and that's what I've done," Gay told Rai television.
"I don't know if it is a message to Bolt, it's not 9.69, but I'm pretty sure he knows I'm training and working hard."
Kerron Stewart ran another world leading time of 10.75 and her personal best in the women's 100m to beat fellow Jamaican and Olympic champion Shelly-Ann Fraser.
Victory keeps Stewart in contention for a slice of the $1 million jackpot shared between the athletes who win at all six Golden League meetings after she took the first two.
Ethiopian middle distance great Kenenisa Bekele still has a chance of a slice of the big prize too after clinching the 5,000 metres in 12 minutes, 56.23 seconds, the best time so far this year.
So has Sanya Richards of the United States, who won the 400m in 49.46 to notch her 36th sub-50-second performance, breaking the tally set by World record holder Marita Koch of East Germany.
Russia's Olympic and world pole vault champion Yelena Isinbayeva remains in the hunt too, although her winning mark of 4.85m was well short of her world record of 5.05m.
Norway's two-time Olympic champion Andreas Thorkildsen ended his rival Tero Pitkamaki's million-dollar hopes with a final throw of 87.46m.
Finnish world champion Pitkamaki had led the competition from the start with his first throw of 83.68.
Bahrain's world champion Maryam Yusuf Jamal also set a year-best time of 3:56.55 for victory in the women's 1,500m.
Cuba's 110m hurdles Olympic champion and world record holder Dayron Robles triumphed at his first Golden League event this year in 13.17.
The next Golden League meeting is in Paris on July 17.