However, Phoenix players were quick to inform Gillett that he had confused Riera with Louis Fenton, who had received a yellow earlier in the match.
Riera was recalled but substituted a short time later.
Perth's win lifted them to equal on points with fourth-placed Melbourne Victory.
Wellington remain in ninth spot with just four draws from eight games.
Glory entered the match missing six first-choice players, as well as defender Steve Pantelidis, who signed with Malaysian outfit Selangor FC on Tuesday.
Former French international William Gallas (calf), striker Shane Smeltz (ankle), Josh Risdon (knee), Scott Jamieson (Achilles) and Ryo Nagai (calf) were all injured, while Jacob Burns was missing through suspension.
The lengthy list of absentees handed 16-year-old Danny De Silva his first A-League start.
De Silva and Sidnei were full of run early as Wellington's defence struggled to keep tabs on Glory's speedsters.
Sidnei opened the scoring in the 16th minute with a 20m curling effort that left goalkeeper Moss with no chance.
But the visitors hit back against the run of play in the 36th minute when Huysegems unleashed his own bullet from the edge of the box.
A glancing header from Ifill gave Wellington a shock lead in the 49th minute, but Perth scored three goals from that point on to secure the win in front of 8232 fans.
-AAP