Real Salt Lake is a few days shy of the two-year anniversary of its last league loss at home, but the challenge of continuing that dominance just became much more difficult.

A gruesome ankle injury will sideline star midfielder Javier Morales for at least four months, leaving RSL with a major hole to fill as it tries to extend its regular-season unbeaten run at Rio Tinto Stadium to 29 on Saturday against the Houston Dynamo.

Salt Lake (5-1-0) has played the fewest MLS games of any Western Conference team, mainly because of its advancement deep into the CONCACAF Champions League.

After a crushing 1-0 home loss in the second leg of the finals to Mexican club Monterrey, RSL returned to league play April 30 with another 1-0 defeat, this time on the road against expansion Portland.

RSL's home unbeaten streak in MLS play was still intact when it hosted Chivas USA last Saturday, but there was no cause for celebration despite extending the run to 28 with a 1-0 win on Will Johnson's 87th-minute goal. That's because a tackle from behind by Chivas forward Marcos Mondaini late in the first half fractured Morales' ankle, requiring a cart to wheel off RSL's top playmaker.

"We won," midfielder Collen Warner told the league's official website. "But it feels almost like a loss."

Morales, who has had a hand in four of RSL's nine goals, had surgery Monday. October is the earliest he could be back on the field - a timetable that could have him back for a potential playoff run - but it's possible he might not return until 2012.

Mondaini, meanwhile, was suspended four games - six fewer than Colorado's Brian Mullan for a similarly dangerous tackle that broke the leg of Seattle's Steve Zakuani.

"It's tough, man," midfielder Kyle Beckerman. "He's the best player on our team, and one of the best in the league. So it's not only bad for us, it's bad for the league that he's not going to be playing."

Morales' injury should give RSL plenty of motivation to prove it can overcome his absence while trying to avoid its first MLS home loss since May 16, 2009.

That could spell trouble for a Houston team that hardly looks on top of its game after going 3-0-2 in April. The Dynamo (3-3-3) blew a late lead in a 2-1 home loss to Colorado on May 4, then fell by the same score last Saturday at Toronto.

"We had a lot of chances but couldn't find a way to score," midfielder Brad Davis said. "Every chance right now teams are getting, they're scoring, and we go down and can't score at all."

Getting on the board at Rio Tinto Stadium isn't easy for any visitor. RSL has conceded just four goals in its past 14 home games, but Dynamo forward Cam Weaver thinks his club won't be intimidated.

"Our team looks at it as a challenge for us to go in there and put an end to that streak or to put in a good performance and get a good result," Weaver said.