The 18-year-old Guerrero dominated her favorite event - the womens 200-m breaststroke where she clocked two minutes and 44.89 seconds for the gold. Her victory came on a day powerhouse Thailand ruled Day One of the swimming competition.
So overpowering was Guerrero that her winning time was way ahead of Thailands Tachaporn Iamsanitamorn (2:49.64) and Vietnams Nguyen Phoung Thrang (2:97.09).
But Guerreros triumph was overshadowed by the Thais, who jumpstarted their title-retention bid by winning seven of the eight gold medals disputed on opening day, including one by Guerreros victim - Iamsanitamorn - in the womens 100-m butterfly.
Chorkaew Choompol emerged as Thailands first double gold medalist after she topped the womens 400-m freestyle and 100-m backstroke in lopsided fashion.
Choompol registered a time of 4:35.43 in the freestyle event before bagging her second gold in the backstroke with a time of 1:09.29.
Thailands other gold medalists were Wattapong Tongpawee (mens 1,500-m freestyle), Piyawat Kraithumjthkul (mens 100-m backstroke), Vorrawatti Aumphiwan (mens 200-m breaststroke) and Teonpong Boonsmikatsawad (mens 100-m butterfly).