Despite making the PBA All-Rookie Team with Phoenix, he would return to the MPBL in 2023, playing for the Pampanga Giant Lanterns.
[3][4] Serrano eventually finished his high school career with the La Salle Green Hills (LSGH) Greenies of the National Collegiate Athletic Association (NCAA) for Season 93.
When the league turned pro in August that year, Serrano didn't apply for a Special Guest License from the Games and Amusements Board.
Thus, he didn't play in the Finals series against the La Union PAOwer, which the Delta ended up winning.
[12] Staying in the grassroots, Serrano joined the Basilan Jumbo Plastic for the Maharlika Pilipinas Basketball League's 2021 Invitational tournament.
[15] Serrano was declared the MVP of the draft combine and would go on to be selected by the Phoenix Super LPG Fuel Masters with the 19th overall pick.
[17] Serrano averaged 10.3 points, 3.7 rebounds, and 1.9 assists per game, and was selected to the PBA All-Rookie Team.
[20][21] He was initially listed as part of the team's roster ahead of the 2023 MPBL season on April 10, but didn't make his debut until June 15.
[23][24] In his second season, Serrano continued to play a key role, averaging 12.7 points, 3.2 rebounds, and 3.1 assists per game.
[25][26] Despite that, it didn't slow down PGL's chances at clinching back-to-back titles, giving Serrano his fourth championship overall.