"For me, the proof is always in the 90 minutes," he said. "These guys work hard every day. I have no complaints about the work they put into any training session. ... But they need to put it in tomorrow night."
The Whitecaps played to a 2-2 draw last Saturday and then had to follow that up with a midweek match. Vancouver beat Edmonton FC on Wednesday to advance to the finals of the Amway Canadian Championship.
Kreis, however, is not expecting that to hurt them tomorrow.
"I think there's a physiological output that your body is capable of making," he said. "For me, three games in a week is not ideal for our sport. But I know Vancouver did a lot of rotating players Wednesday night. I don't think fatigue should hurt them."
RSL got a glimpse of Vancouver's attacking speed last month, and is expecting more of the same from the Whitecaps on Saturday.
"I think it's going to be tough to keep them off the scoreboard," defender Nat Borchers said. "They've got Darren Mattocks, who provides a spark for them. He's quick, man. He's a lot faster than you expect him to. He gets to some balls that most strikers don't get to. We're going to have to be aware of him and Camilo [Sanvezzo] and [Nigel] Reo-Coker and anybody else who comes in to our zone."
RSL's Olmes Garcia trained fully Friday despite being listed as questionable this week with a groin injury. Forward Robbie Findley, however, was not a full participant as he deals with a knee injury. Leading goal scorer Alvaro Saborio is out for Saturday's match with a quad strain.