Arena fumes as Pappa's injury time screamer sees Rapids beat Galaxy

"That's a 93-minute game at the most and to lose in the 95th minute is a crime," Arena told reporters after Marco Pappa's strike gave the home side the win.

"It's disgraceful, it really is ... Bad judgment by the fourth official not to question it."

The goal came after Galaxy defender Daniel Steres' attempted clearance fell straight to Pappa.

"Just a bad clearance spun off my head, fell right to their guy and quite a finish," Steres said. "We were just trying to bunker down and see out the end of the game."

Match-winner Pappa, who was the victim of a stabbing in December, savoured the win and said he was trying to move on from the incident.

"Nobody likes to talk about the bad things that happen in your life," Pappa said, adding that he was focused on his football and family.

In Montreal, Ignacio Piatti netted his third goal of the season to lead the Impact to a 3-0 win over New York Red Bulls.

Dominic Oduro and Anthony Jackson-Hamel also netted for Montreal.

"We need everybody, and we all came out here to play," Oduro said. "That's what's important right now. We have momentum from last year, and it's really positive. We're playing well, with help from Mauro (Biello) and his coaching staff."

Houston Dynamo enjoyed the day's biggest win, crushing Texan rivals FC Dallas 5-0.

Houston netted four goals inside the opening half hour in a superb performance, and capped it off with a fith in the closing five minutes.

Colorado Rapids 1 LA Galaxy 0

Columbus Crew 1 Philadelphia Union 2

Houston Dynamo 5 FC Dallas 0

Sporting Kansas City 2 Vancouver Whitecaps 1

Montreal Impact 3 New York Red Bulls 0

New England Revolution 0 DC United 0

Real Salt Lake 2 Seattle Sounders 1