DeLaGarza, 27, missed the second leg of the Galaxy's 2-1 loss at the Seattle Sounders due to a hamstring injury, but the result was enough to send them through on away goals.
The defender said the turf at CenturyLink Field and freezing cold were the reasons he was unwilling to risk his hamstring.
"I feel a lot better, will be ready to play this weekend," he told a media teleconference.
"It was just a factor of [the artificial] turf and the weather was not good to go out there.
"You saw Ozzie Alonso had two weeks to prepare for that, and he was still struggling with his hamstring.
"I thought it was smart on our behalf just to get a guy in there who's fresh and ready, and it paid off at the end, and we won."
DeLaGarza said Sunday's clash in Seattle perhaps came too soon for his return.
"I'm a defender, not an attacker, so if I was someone that needed to play and score goals, then maybe," he said.
"But as a defender, I think you need someone back there who's ready and 100 percent or close to it."
