Darlington Nagbe scored in the 52nd minute and the Portland Timbers ran their MLS unbeaten streak to 13 games with a 1-0 victory over FC Dallas on Saturday.
Portland (6-1-8, 26 points) pulled within two points of Western Division-leading Dallas (8-3-4).
Portland hasn't dropped a match since losing to Eastern Division-leading Montreal 2-1 on March 9.
The victory Saturday was the Timbers' sixth during their club-record 13-match unbeaten streak.
Dallas lost for only the second time in its past 13 games, but both defeats came on trips to the Pacific Northwest. Dallas lost at Seattle 4-2 on May 18.
Portland won the season series over Dallas, with the teams playing to a 1-1 tie May 8. The Timbers play at Dallas on June 26 in the U.S. Open Cup quarterfinals, a non-counting MLS match.
The Timbers' lone goal was set up early in the second half when Kalif Alhassan passed to Nagbe in the penalty box. Nagbe pivoted to his right and blasted a 12-yard shot into the top right corner of the goal.
Both teams had several good chances to score in the first half. Portland's best came during the 15th minute when Diego Valeri's header off a cross from Michael Harrington hit the cross bar. Dallas threatened seconds before halftime, but Timbers keeper Donovan Ricketts deflected Jackson's 20-yard rocket shot.
Portland had several chances to add to its lead after Nagbe's goal. The best was a breakaway during the 77th minute by Diego Chara, whose 10-yard shot glanced off the right post.
Dallas' best chance to tie came during the 72nd minute when Jackson broke away from two defenders, but his 15-yard shot sailed over the crossbar.
Dallas starting forward Kenny Cooper did not play. Cooper flew back to Dallas on Saturday morning to attend to a family emergency. Eric Hassli started in his place, but he left during the seventh minute with a leg injury.