Sporting Kansas City and the Portland Timbers kept their respective unbeaten runs intact in a 0-0 draw on Saturday night at Portland's Providence Park.
The Timbers are now 6-0-2 in their eight matches without a loss, the longest such active stretch in the Western Conference and second longest in the league behind Columbus' nine-game run.
But Saturday's draw was the second straight at home after a 1-1 tie against the 10-man LA Galaxy a week ago.
Meanwhile, SKC are 3-0-3 in their last six matches, and leave Portland tied for the Western Conference lead with FC Dallas after Dallas' 2-0 victory over Montreal earlier on Saturday.
Visiting Kansas City had arguably the better chances over the course of what was their second scoreless draw in three matches, and the only clear opportunities of the first half.
In the 27th minute, Gerso Fernandes' cross found Johnny Russell alone in front of the goal, but Russell's glancing header sailed well wide of the frame.
Then in the 41st, Daniel Salloi got hold of a misplayed ball by Russell and drove a shot that rattled keeper Jeff Attinella's crossbar.
Portland gained some momentum in the opening stages of the second half and had two of their best chances in a two-minute stretch.
Goalkeeper Tim Melia dove left to push away Fanendo Adi's 56th-minute header, and then held Cristhian Paredes' effort from distance in the 58th despite a tricky hop off the ground.
For Adi, it was his only effort on goal in his return to the starting lineup, after being dropped at forward for Samuel Armenteros in Portland's last two matches.
On the other end, Russell curled a free kick a foot wide of the left post in the 65th minute, and Roger Espinoza's drive toward the bottom left corner forced Attinella into a diving stop in 73rd minute.