Weidman, according to UFC officials, suffered a hand injury in training, leaving him unable to compete at UFC 181.
Making lemonade out of lemons, the UFC acted swiftly, replacing the Weidman vs. Belfort main event with the return of welterweight champion Johny Hendricks, who will rematch Robbie Lawler in the new UFC 181 headliner.
Hendricks won the then-vacant welterweight championship by defeating Lawler at UFC 171 earlier this year in March.
Lawler earned a second shot at Hendricks and the belt by winning back-to-back bouts over Jake Ellenberger and Matt Brown, while Hendricks was on the mend from a torn biceps muscle.
Hendricks recently gained clearance to return to fighting, but the question then became when the UFC could slot the fight with Lawler into its already loaded schedule, as the Hendricks vs. Lawler bout is one that the company wanted to headline a pay-per-view event.
UFC 181 will be co-headlined by the lightweight title bout between champion Anthony Pettis and top contender Gilbert Melendez, following their run as head coaches on the current season of The Ultimate Fighter.
Tickets for the newly revised UFC 181: Hendricks vs. Lawler II go on sale to the general public this Friday with UFC Fight Club members getting an early shot at tickets on Wednesday. The tickets range in price from $125 up to $1,000.