The New York Red Bulls and Sporting Kansas City extended their winning runs in MLS as Real Salt Lake lost again.
An own goal by Dallas' Brazilian midfielder Erick was enough for the Eastern Conference-leading Red Bulls, who claimed a 1-0 win in New Jersey.
Jonathan Steele's cross caused more problems than it should have for the Dallas defence and Erick's miscued clearance was unstoppable in the 76th minute.
Victory kept Mike Petke's New York three points clear at the top despite Sporting Kansas City's 2-1 win at Toronto.
CJ Sapong scored a brace for Sporting against a Toronto side who finished the season with 10 men after Steven Caldwell was sent off on 86 minutes.
Sapong opened the scoring on 18 minutes when he nodded in Dom Dwyer's headed pass before Darel Russell levelled seven minutes prior to the break.
Sporting goalkeeper Jimmy Nielsen's sloppy pass turned over possession and led to Russell finishing into the bottom corner from the edge of the area.
Sapong headed in the 53rd-minute winner as the rain came down at BMO Field.
Real Salt Lake suffered a second straight loss as Steven Lenhart's brace saw the San Jose Earthquakes to a 2-1 win.
The Montreal Impact's poor form continued as they were handed a 3-0 thrashing by the Vancouver Whitecaps.
It marked Montreal's third straight loss in all competitions and sees them slip six points behind the Red Bulls.
The Portland Timbers recorded a 1-0 win at home to the Colorado Rapids and the New England Revolution claimed a come-from-behind 2-1 victory at home to DC United.
The Columbus Crew comfortably overcame a 10-man Chicago Fire and Giles Barnes and Boniek Garcia's braces led the Houston Dynamo to a 5-1 thrashing of Chivas USA.
Juninho's 45th-minute effort was not enough for the Los Angeles Galaxy, who were held to a 1-1 draw by the Seattle Sounders.