Baby Boomer Cheers on Dad Michael Phelps as He Swims to His First Gold Medal in Rio

Michael Phelps competed in the men's 4x100-meter relay

Photo: Adam Pretty/Getty Images

Michael Phelps made his Rio debut a little ahead of schedule.

While the 31-year-old Olympian is set to compete in the men’s 200-meter butterfly heats on Monday night, it was announced on Sunday night that he would compete in that night’s 4×100-meter freestyle relay just hours before the race.

Phelps competed with his fellow Team USA swimmers Nathan Adrian, Ryan Held and Caeleb Dressel. The team held a slight advantage over the other teams.

Phelps’ family, including his son Boomer, could be seen cheering him on from the stands.

Ahead of his Rio debut, Phelps already held the all-time record for the most Olympic gold medals (18), Olympic gold medals for individual events (11) and Olympic medals in individual events for a male athlete (13). The elite athlete had previously said that the 2012 London Olympics would be his last, but he came out of retirement in 2014 and went on to easily secure a spot on Team USA once again.

For more of PEOPLE’s Olympic coverage, pick up our collector’s edition, The Best of the Games, on sale now.

This year’s Olympics was already home of a few firsts for Phelps – he served as the flag bearer for his first-ever march with Team USA during the Opening Ceremonies and it also marks the first Olympics since he became a dad to baby Boomer.

RELATED VIDEO: Does Michael Phelps Already Have a Future Olympic Swimmer on His Hands?!

Phelps has a full schedule ahead of him. On Monday he will compete in the 200-meter butterfly, on Wednesday he will race in the 200-meter individual medley and on Thursday he will face off in the 100-meter butterfly.

To learn more about all Olympic hopefuls, visit teamusa.org. The Rio Olympics begin Friday on NBC.