Although the exact nature of the injury was not known by the time the game was over, Morales had to be taken off the field on a stretcher after suffering what appeared to be either a broken leg or ankle.
The injury came when he was tackled from behind by Marcos Mondaini, who was immediately kicked out of the game. Chivas defender Andrew Boyens also earned two quick yellow cards and his team had to play with only nine men for more than half the contest.
Johnson's goal came just 3 minutes before the end of the contest, boosting Salt Lake to a 5-1 record. It was the team's fourth shutout this season. Chivas fell to 2-3-3.
Morales became the third star player in Major League Soccer to suffer a significant injury this year, joining reigning MVP David Ferreira of Dallas and Steve Zakuani of Seattle.