It's difficult to say where the Colorado Rapids would be lately without Conor Casey, whose goal-scoring binge has helped them to a five-match unbeaten streak.
They weren't expecting to have to find out.
Casey's last-minute call up to the United States national team will keep the MLS goal-scoring leader out of Saturday's road match against Real Salt Lake, which is also going to be searching for offense as it tries to end a six-game winless skid.
After his two-goal performance in last Saturday's 3-2 road win over the New York Red Bulls, Casey now has four goals in his last three games, boosting his season total to eight.
"He's been absolutely terrific," Colorado coach Gary Smith said. "He's been carrying a sore foot and he's had a difficult year after a broken bone in the summer in his foot. To a degree, we've been nursing him through the week, but when he counts like that, I'd play him in a concrete boot just to get him out there.
"He's in one of those veins of form right now and I don't want to put the markers on him, but he looks very sharp in front of the goal."
Smith will have to find offense from somewhere else against RSL, be it starting forward Omar Cummings or another source. With U.S. forward Brian Ching dealing with a hamstring injury, Casey was added to the national team's roster as insurance.
Colorado will also be without captain Pablo Mastroeni, who was already with the U.S. national team for its World Cup qualifying match Saturday against Honduras.
That leaves the Rapids (4-2-4) lacking perhaps their two best players as they try to extend their unbeaten run. They have gone 2-0-3 since a 1-0 defeat at Houston on April 19, scoring nine goals in those games.
The stretch includes a 2-0 home win over RSL (3-6-2) on May 2, meaning that a victory Saturday would clinch the Rocky Mountain Cup for Colorado for the first time since 2006.
The loss in Colorado began Salt Lake's 0-4-2 month of May, during which the team scored three goals and slumped to sixth place in the Western Conference. RSL had been shut out three straight times before Robbie Findley scored his sixth goal in last Saturday's 2-1 loss at San Jose.
Findley's goal was the club's first on the road this season, but Real has been much better at home. It has outscored opponents 14-6 while going 3-1-1 at Rio Tinto Stadium, with the goal differential boosted by a 6-0 win over New England on April 25.
"I think we play with a bit more confidence, a bit more flair, a bit more everything when we play at home," coach Jason Kreis said.
Like the Rapids, Salt Lake will have to overcome the absence of two starters. Midfielders Kyle Beckerman and Javier Morales will miss the match due to suspensions.