Just two minutes after coming off the bench, Montero found the back of the net for the eighth time in league play. Mauro Rosales took a free kick from about 35 yards out, but instead of going on net, chipped it into the penalty area. Defender Jeff Parke played the ball off his chest and directed it to Montero, who got just enough of his toe on the shot to bounce it past Vancouver goalkeeper Joe Cannon.
Johnson scored on a counter attack off a cross from Brad Evans in the closing minutes for his 11th goal of the season.
Seattle moved three points clear of the Whitecaps and Los Angeles and into third place alone in the conference standings. Seattle has played two fewer games than both the Whitecaps and Galaxy.
Montero's goal gave Seattle a deserved result after the Sounders held the better of the scoring chances. Two times earlier in the second half Seattle had point-blank chances that never found the net. Osvaldo Alonso's shot inside the penalty area in the 52nd minute was blocked away by Vancouver defender Carlyle Mitchell. A minute later, Johnson found himself wide open on the end of a cross from Adam Johansson, but tried to volley the pass and shanked it wide of the net.
But Montero was able to make sure Seattle got the three points it needed, helping erases the bad taste of last week when the Sounders lost the U.S. Open Cup final to Sporting Kansas City on penalties, then dropped a 2-1 decision to league-leading San Jose by surrendering the winning goal three minutes into second-half stoppage time.
Montero was the hero for Seattle in May when the Pacific Northwest rivals met for the first of three matches this season. Montero's 90th minute goal in Vancouver allowed Seattle to pull out a 2-2 draw with the Whitecaps in the first match. The Whitecaps will host Seattle on Sept. 29 in their final matchup of the regular season.
Vancouver lost for the third time in its last four league matches and second straight following a 2-0 loss to FC Dallas at home on Wednesday. And the Whitecaps were playing decidedly short-handed. They were already without defender Martin Bonjour, who picked up his sixth yellow card against Dallas on Wednesday and was suspended for the match. Then the league announced Saturday morning that designated player Barry Robson would be suspended for the match for his treatment of an assistant referee in the loss to Dallas.
And captain Jay DeMerrit missed his second straight match after suffering a concussion Aug. 11 in the first half against Real Salt Lake.
The Whitecaps momentarily appeared to pull even in the 81st minute when Darren Mattocks knocked a rebound off Seattle goalkeeper Michael Gspurning into the net, but Hendricks fouled defender Jeff Parke on the play and the goal was waved off.