COMMERCE CITY, Colo. -- The Colorado Rapids could be without another key starter for Saturday’s trip to Vancouver.

Already down several defenders for this weekend, Colorado will also likely be without talented young midfielder Dillon Serna, who’s expected to miss out with a sprained ankle once again this weekend against the Whitepcaps (6:30 pm ET, MLS Live).

“I don’t think he’s quite ready,” Rapids head coach Pablo Mastroeni said of Serna on Wednesday. “My gut at the moment tells me it might be better to save him for a grass field versus a turf field. Especially with a sprained ankle.”

Serna sprained his ankle in practice two weeks ago and has missed each of the Rapids’ previous two matches after making his MLS debut in the season opener. The 19-year-old Homegrown product impressed in his debut, generating several chances in Colorado’s 1-1 draw with the New York Red Bulls.

But even with an improved sprained right ankle, Serna anticipates returning on April 12 in Toronto rather than this weekend.

“It’s doing a lot better,” Serna told MLSsoccer.com. “I’ll be ready for Toronto for sure.”

Finding Serna’s replacement, meanwhile, could be a trickier than expected. Veteran Vicente Sanchez, who has a league-leading four goals (all from the penalty spot), may not play on Saturday due to the turf at BC Place, and Mastroeni said on Wednesday that he might rest the 34-year-old to avoid wear and tear.

If Sanchez can’t go, veteran Marvin Chavez or 19-year-old Charles Eloundou could suit up in his place.

“We want to make it a 40-game season,” Mastroeni said. “Looking at the big picture, the first three games of our campaign have been very grueling from the mental and physical aspect. So it might be a good opportunity to look at [resting veterans] a little bit more closely. We’ll make those decisions come Friday and go from there.”

Chris Bianchi covers the Colorado Rapids for MLSsoccer.com.