The Liverpool legend was one of four club greats to join the first team on the pitch in their friendly against Sydney FC, which was won 3-0 at the ANZ Stadium.
Firmino shook off a long flight to star in the opening 45 minutes, teeing up Alberto Moreno to score the second goal with a delightful dinked assist before prodding home the third in front of more than 70,000 fans.
Gerrard featured for the duration of the first half Down Under and was particularly grateful to play with the No.11, who joined the Reds in the summer of 2015 as the former captain departed for Los Angeles Galaxy.