Adam Gemili ran his first sub-10 seconds 100m but then fell to the ground with a suspected torn hamstring.
The 21-year-old ran 9.97 secs in Birmingham to become the first Briton to go under both 10 seconds in the 100m and 20 seconds in the 200m.
He clutched his leg after crossing the line in second place behind American Marvin Bracy (9.93) and was taken from the track in a wheelchair.
Dina Asher-Smith, 19, ran the second quickest 200m by a British woman.
On a successful day for Britain’s sprinters, Asher-Smith finished third in a personal best 22.30 secs.
The British 100m record holder was just a hundredth of a second adrift of winner Jeneba Tarmoh and Allyson Felix in second, who both clocked 22.29 secs.
“I’m really happy,” Asher-Smith told BBC Sport. “I was looking to get somewhere around my personal best so to run 22.30 is just out of this world.”
The pair’s performances sated athletics fans in the absence of double Olympic champion Mo Farah, who withdrew from men’s 1500m on the morning of the competition.
Farah said he was “emotionally and physically drained” after a “stressful week” that saw a BBC investigation allege his coach Alberto Salazar had been involved in doping.