The two American sprinters clocked 9.86 seconds, while two other runners went sub-10 in a fast final.
Noah Lyles claimed a sensational photo-finish victory in the 100m at the IAAF Diamond League athletics meet in Shanghai, edging out compatriot and last year's Diamond League Final champion Christian Coleman at the line.
The winning time of 9.86 seconds was a new personal best for the 21-year-old Lyles, who shaved 0.02 seconds off his previous mark, set at least year's U.S. nationals.
Lyles started slowly out of the blocks as Coleman gained an early lead, but the younger man finished strongly, using his larger stride effectively to just nip ahead of his 23-year-old rival as they crossed the finish line.
Both men were awarded the same time, which is the new world leading time this year. Lyles also now holds the meet record for the Shanghai Diamond League event.
It was the first time since he finished fourth at last year's Rome Diamond League at the end of May that Coleman, whose personal best is 9.79 seconds, failed to win a 100m race he started.
South Africa's Akani Simbine and British athlete Reece Prescod, third and fourth respectively, both also clocked sub-10-second times in a fast final.
Asian record holder and home favourite Su Bingtian finished fifth.
Qatar's Abderrahman Samba and Rai Benjamin, making his Diamond League debut as a member of the U.S. team, faced off for the first time.
The pair were evenly matched through the first three-quarters of the race before Samba pulled away on the final straight to win in a world-leading 47.27 seconds.
World record holder Beatrice Chepkoech was no match for the rest of the field in the women's 3000m steeplechase.
The Kenyan had established a lead early and, by the time there were two laps to go, had an advantage of almost 25 metres.
She clocked 9:04.53 to take nearly 35 seconds off the previous world lead time this year.