Updated

Portland, OR (SportsNetwork.com) - The Portland Timbers moved to the top of the Western Conference on Sunday after a 1-0 home win over Seattle Sounders FC courtesy of Kalif Alhassan's 45th-minute goal.

Seattle entered the match with a chance to clinch a playoff spot with a win over Portland, but the Sounders dropped to third in the West with their third straight defeat.

Portland extended its unbeaten run to six games with the win and moves one point clear of second-place Real Salt Lake.

The best spell of the game for the Sounders came in the opening 15 minutes as a flicked header from Lamar Neagle forced Portland goalkeeper Donovan Ricketts into a fine diving save at the top corner of the net.

One minute later Seattle's Clint Dempsey headed a chipped pass from Adam Moffat off the crossbar, but the Timbers survived the early pressure.

Just before halftime Portland went in front when Jack Jewsbury floated a ball into the penalty area that wasn't cleared by the Seattle defense, allowing Alhassan to smash a shot inside the left post.

Portland sat back a little deeper after halftime and Seattle was reduced to 10 men when Osvaldo Alonso received a red card for elbowing Portland's Will Johnson away from the ball.

Despite the numerical disadvantage Seattle was unlucky not to leave Jeld-Wen Field with a point as substitute Steve Zakuani saw his deflected effort in stoppage time come back off the crossbar.