Velasco, who missed all of last season with a left-knee injury, said the Tigers wanted to dictate the flow of the match early.
"In the first 20 minutes, we wanted to get things done," said Velasco, who took a pass from Jessica Moog and bounced a shot past Burbank starting goalkeeper Sarah Rangawala to give the Tigers a 1-0 lead in the fifth minute. "We started out strong, and we wanted to let the other team know we were ready right away.
"Getting that first goal was great. I'm trying to make this my best year athletically. It was painful to have to watch the games and not play last season. Soccer has been my life."
South Pasadena made it 2-0 when a centering pass by Kelly Brady bounced off Muller, who was sliding to defend in the 16th minute.
Burbank cut the deficit in half when Gabby Dixon corralled a loose ball and beat South Pasadena goalkeeper Angelique Ulmer in the 30th minute.
Keenan closed out the scoring in the 36th minute.
Burbank Coach Eric Montoya said the Bulldogs (2-1) couldn't catch any breaks, especially in the first half.
"Some of their goals came because of defensive mistakes," said Montoya, who received three saves from Rangwala and two from reserve goalkeeper Brianna Jacobo. "We got back into it at 2-1 and we were halfway up the mountain, and then we give up that third goal and we are at the bottom of the mountain.
"I liked the way we played. We have some things to work on, but I'm glad they are learning and not opting to hang their heads."
Burbank had a good scoring opportunity in the third minute. Maddie Carlborg turned inside the box and lined a 12-yard shot that was steered aside by Ulmer.
Rangwala's best save came in the 15th minute. Velasco got around a Burbank defender and lined a shot toward the left side of the net that Rangwala stopped.
Lilavois, the reigning All-Area Girls' Soccer Coach of the Year, said the Tigers' experience played a role in turning back the Bulldogs.
"We have a lot of returning players, so we have a lot of firepower and people who can score," Lilavois said.