Johan Venegas broke a second-half deadlock as Montreal Impact rallied to beat Columbus Crew 2-1 in the first leg of the MLS conference semi-finals.

Venegas dispossessed Crew defender Michael Parkhurst and ran through on goal before curling the ball beyond Steve Clark with 13 minutes remaining in the Eastern Conference semi-final at Stade Saputo in Montreal.

Scores were level at half-time in the play-off clash after Impact midfielder Patrice Bernier cancelled out Federico Higuain's 33rd-minute opener within four minutes.

Didier Drogba was unable to add to his 12 goals this season, despite finding the back of the net in the first half.

The former Chelsea striker's 15th-minute goal was ruled out for handball just as he turned away to celebrate.

Drogba and Company will travel to Columbus for the return leg next Monday (AEDT).

Seattle Sounders were also 2-1 winners on home soil courtesy of a stunning late free-kick from Clint Dempsey.

The United States international struck three minutes from time to see the Sounders past visiting FC Dallas in the Western Conference.

Fabian Castillo put Dallas ahead inside 18 minutes after being played in behind Seattle's defence by team-mate Mauro Diaz.

The Sounders were back on level terms in the 67th minute, when Andreas Ivanschitz fired the ball across Dallas goalkeeper Jesse Gonzalez from outside the box.

Dempsey completed the comeback in the closing stages, with a curled set-piece beyond Gonzalez.

New York Red Bulls netted a priceless away goal in their 1-0 win at DC United.

Dax McCarty's 72nd-minute goal was enough to see off DC in the American capital.

Sacha Kljestan whipped in a deep free-kick and picked out McCarty, who headed past Bill Hamid.

Meanwhile, Portland Timbers were held to a goalless draw at home to Vancouver Whitecaps.