As the Portland Timbers' practice was winding down Tuesday, projected starting goalkeeper Troy Perkins stood in the goal box, defending point-blank shots by teammates as the players worked on finishing goals.
Timbers coach John Spencer rolled a ball to striker Kenny Cooper. Cooper fired a laser beam toward the goal. The ball hit Perkins on the side of his right knee - which was planted in the wet grass of Delta Park, where the Timbers have been practicing. Perkins' knee bent to the side, and he crumpled to the pitch, writhing in pain.
As a stony-faced Spencer looked on, trainers looked at Perkins. After seeing that Perkins was able to bend his knee with what appeared to be a full range of motion, the trainers escorted Perkins off the pitch as he hobbled with arms wrapped around a teammate on each side of him.
Perkins did not participate in training on Thursday and is expected to miss perhaps three weeks, including the Timbers' MLS opener Saturday on the road against the defending champions, the Colorado Rapids.
Adin Brown, 32, and Jake Gleeson, 20, are Perkins' backups at goalkeeper. Brown is the likely starter on Saturday.
The injury to Perkins showed how fragile things can be for a team like the Timbers.
Darlington Nagbe, the second overall pick in the 2011 MLS SuperDraft, is likely to miss the first match after undergoing surgery for a sports hernia.
Sal Zizzo, the projected midfield starter also will be a game-time decision after separating his shoulder in a 1-1 draw against San Jose on March 12.
'He's alive, breathing,' Spencer said of Zizzo, with a smile. 'He's a game-time decision. He took a little bang on his shoulder.'
Injuries to key cogs or not, Spencer said he expects the players who are healthy will be ready for the Rapids.
'If you're not excited about stepping out Saturday and playing a game in Colorado, playing against the MLS Cup champions, you shouldn't be involved in professional sports,' Spencer said.
Colorado has a solid midfield that includes Pablo Mastroeni. Last season, Mastroeni scored two goals and had three assists. He was recognized as the Rapids' MVP for the third time in his career. The Argentinean-born player of Italian heritage has earned 65 caps with the U.S. national team.
'Pablo Mastroeni has been a national team player for a number of years,' Spencer said. 'He creates the tempo and the energy.'
The Rapids also have a lethal striking combination with Conor Casey and Omar Cummings. Last season, Casey knocked in 13 goals and collected six assists, and Cummings led the Rapids with 14 goals.
'Connor Casey and Omar Cummings up top, they're probably the best tandem in the league, partnership-wise,' Spencer said. 'And they proved that by winning the MLS Cup last year.'
In the offseason, the team that exceeded expectations by going all the way in the playoffs last year added some depth at different positions.
Saturday's match, set to start at 6 p.m. PT, will mark a homecoming of sorts for Spencer, who played for the Rapids from 2001-04.
'I lived there for four years, and I have some great memories,' he said.
Before Saturday's match, the Rapids plan to raise their championship banner.
'It's fantastic that they're getting their rings,' Spencer said. 'It's a nice reminder of what's gone by. What our players must remember is it's in the past. We have to try to create our own future and not let Colorado stand in our way Saturday night.'