Instead, she was rushed to hospital.
While Jade Thirlwall, Leigh-Anne Pinnock and Jesy Nelson performed together in Las Vegas, Perrie was suffering from a gastric problem.
"Perrie was taken ill overnight and had to go to hospital with gastric problem. She saw a doctor and was sadly unable to perform," the band's rep said to Daily Mail in a statement.
None of the girls, nor Perrie have made any public comments, but we're pretty sure that she is doing fine.