Dom Dwyer got the goal and Tim Melia preserved the win for Sporting Kansas City.
Dwyer scored in the 53rd minute and undefeated Kansas City won its first game on the road this season, a 1-0 victory over the Portland Timbers on Saturday night.
Melia was able to tip a hard shot from Darlington Nagbe in the 79th.
"I thought from the opening whistle we came to play, I thought we worked really hard and I thought we were very intelligent in the game," Sporting coach Peter Vermes said. "I thought we managed the moments of the game really well."
Kansas City remained one of just two teams in Major League Soccer without a loss. It was the team's fourth shutout of the season.
Sporting's stout defense, which has allowed only two goals through six games, slowed a Portland side that leads the league with 16 total goals. Fanendo Adi and Diego Valeri have five goals each but neither was able to get anything going.
It was Portland's first loss of the year at Providence Park.
"That's a very good team," Portland coach Caleb Porter said. "This game will help us. We'll learn from it. And we'll have a chance next weekend to show we've learned some lessons from this type of soccer game."
The Timbers (4-2-1) were coming off a 3-1 victory at Philadelphia. Adi scored his 46th goal as a Timber, setting a new club record dating back to 1975, when the team was part of the North American Soccer League.
Sporting KC (3-0-3) was coming off a victory at home last week against the Colorado Rapids. The game has gotten attention in recent days because Colorado goalkeeper Tim Howard was suspended for three games and fined for using profanity directed at the crowd during the match and getting into an altercation with a fan following the game.
Dwyer broke out with his first goal of the season against the Rapids.
Dwyer pestered the Timbers throughout the first half and Kansas City appeared to dominate possession. A corner kick in the 37th minute led to Ilie Sanchez's header from about six yards out that sailed just over the goal for a close call.
A short time later Dwyer's attempt from some 20 years out was off the mark.
Dwyer finally came through with a goal on a header in the 53rd minute off a cross from Jimmy Medranda and got around Portland's Marco Farfan out in front.
"He (Medranda) just whipped it across and I just redirected it into the corner," Dwyer said.
Vermes couldn't believe that Medranda didn't shoot.
"Then Dom, to be able to athletically get himself into position to stick that into the back post — because it's away from home, and it's not their goal, it doesn't get the notoriety it should in the stadium — it was a very, very good goal.
Sporting defender Ike Opara was shown a yellow card in the 25th minute for delaying the restarter after teammate Graham Zusi was called for a foul. Kansas City's Seth Sinovic was shown a yellow in the 52nd minute for unsporting behavior.
Portland turned up the pressure in the final 15 minutes. Darron Mattocks tried unsuccessfully to chip a shot past Melia. Sporting's goalkeeper really came up big moments later when he tipped Nagbe's hard shot from distance, which caromed off the crossbar.
"The message to the team was, 'We've got to find ways to win games when things aren't going our way,'" Porter said. "And part of that is putting the game on our terms. Part of that is finding a way to win, no matter what. Part of that is managing the emotion of what's happening in the game and keeping your composure."