Nick Rimando and Kyle Beckerman had stayed home, in favor of Jeff Attinella and Yordany Alvarez.
Chris Wingert, Ned Grabavoy and Joao Plata were left to come off the bench.
In all, Kreis made 10 changes to his starting lineup from a week ago, hoping to give his usuals some extra rest.
It hardly made a difference.
As right back Lovel Palmer streaked down the right side of the field with the ball at his feet, Sandoval made a near-post run and waited for his teammate's cross. The rookie striker used his head for a textbook finish to give RSL a 1-0 lead and, eventually, critical points as the team pushes toward the MLS playoffs.
"We're dangerous still," Sandoval said of the RSL lineup, the same one that Kreis started during Tuesday's reserve game against Chivas USA. "We were confident going into the game that we could get three points."
Kreis said he was conflicted about how to approach Saturday's matchup.
On one hand, the coach worried about saving his starters for Tuesday, a game he conceded was more important to his team's future. On the other, Kreis said he did not believe his team would make the playoffs if it didn't put together positive results in its last four games.
"Our playoff lives aren't secure," Kreis said this week. "I don't feel like if we sit where we're at right now, we're going to make the playoffs. We need points and we need them in the worst way."
The coach gambled and got his way.
After two straight losses, Salt Lake finally put together a winning performance. RSL now has 51 points, becoming the first MLS team in the post-shootout era to reach 50 points and 15 wins in four straight seasons.
Salt Lake's lineup had combined for only 99 starts this season 20 of them coming from midfielder Luis Gil, who found himself playing at the top of the diamond midfield instead of his usual place on the side.
RSL looked comfortable at BC Place, combining passes and attacking the Whitecaps without giving up many opportunities on the other end. Attinella had just one save on the night, but looked confident as he cleared away crosses throughout the match.
"I thought we played really well," he said. "We got the early goal, which was huge for us. We got out to a fast start. To hold that lead, on the road, on a turf field against a team that loves to push numbers forward, couldn't be happier."
R There are 10 changes to the lineup from a week ago, and Nick Rimando and Kyle Beckerman don't play.
• Lovel Palmer scores in the ninth minute off a cross from Devon Sandoval.