Tim Howard will not be able to play in the Colorado Rapids' season opener as his recovery from a groin injury has slowed.
Howard had surgery after suffering "a fracture of the right adductor longus" in November, at which time the club ruled him out for four months.
A return in time to face the New England Revolution on Saturday was always a longshot, with his recovery plan setting a return to training for next week.
But coach Pablo Mastroeni said the U.S. goalkeeper has had a slight setback.
"He was having some pain last week," Mastroeni told the Denver Post. "The medical staff, we decided to allow that to heal. Had an MRI, everything looks like it's intact, it's good.
"With Tim, we'll take it one day at a time."
Zac MacMath, who started the first half of the season last year before Howard arrived in the summer, will start for the Rapids on Saturday.
Mastroeni also said the team was being cautious with an Achilles injury to top goal scorer Shkelzen Gashi, who missed the Rapids last two preseason games.
"It's a real fickle situation," Mastroeni said. "The last thing I want to do is put Gashi in a position early on in the season where we lose him for the whole year with a torn Achilles, or god forbid something like that. ... We're just kind of babying him at the moment."