Duplantis cleared 5.60m before a failure at 5.85m, and despite that, he then attempted and cleared 5.95m at the first attempt at the London Stadium.
Despite the clearance, the multiple world record holder decided against attempting the next height of 6.04m, feeling a reoccurance of a thigh injury he picked up in Budapest in midweek, with his left leg heavily strapped.
"I felt it a few days ago after the competition in Budapest. At first it felt completely okay on the track, but then it came right away and it got much worse on the next jump. But I knew I couldn't jump after the 5.95 attempt," he told Swedish television, but was clear to point out he didn't consider it a serious injury.
Sam Kendricks of the USA was the winner of the event - after clearing 5.95m he failed three times at 6.04m but zero fouls before that meant he pipped Mondo to the win, ahead of Kurtis Marschall of Australia and Greece's Emmanouil Karalis, both of whom had more failures before going clear at 5.95m.
Five-time Diamond League champion Duplantis has won just three of the seven pole vault competitions in this year's league.
