Their championship beatdown in Toronto last December and an offensive pit of misery ever since had convinced Sounders coach Brian Schmetzer a change in tactics was needed.

So, when Schmetzer’s team stepped onto BMO Field for Wednesday’s rematch of the last two MLS Cup finals, it was with a five-man defensive backline designed to actually help the team’s attack. And help it did, with the Sounders scoring as many goals in a 2-1 win over Toronto FC as they had their last four-plus matches combined against the defending champions.

Former University of Washington standout Handwalla Bwana put the Sounders ahead to stay in the 54th minute, taking a nifty pass on the run from Will Bruin and beating goalkeeper Alex Bono between the legs.

“It was just the perfect ball,’’ Bwana said, in quotes supplied by a Major League Soccer official. “All I had to do was finish it. The funny thing is I was actually having a good finishing session the day before so I was feeling kind of good.’’

Bwana was one of several youngsters started by Schmetzer, who left all three of his designated players – Clint Dempsey, Nicolas Lodeiro and Osvaldo Alonso – back in Seattle for either injury or rest.

“It’s an unbelievable moment, it’s a kid dream scoring your first professional goal,’’ Bwana said. “I didn’t do it without my team and the most important thing, was getting that three (points for a win) on the board.’’

Beyond the lack of DPs, the only targeted allocation-money player the Sounders started was oft-benched Magnus Wolff Eikrem. The talented midfielder made the most of the opportunity by hitting a striding Bruin with a perfect 25th-minute pass up the middle to set up the game’s first goal.

Bruin collected the ball in behind the defenders and beat Bono to the near post. It was the first goal scored by the Sounders against Toronto after a stretch of 354 scoreless minutes dating to July 2, 2016.

It was also the first Sounders lead against Toronto since their last regular-season victory, 2-1, in September 2015.

“Attacking going forward, they wanted me to drive the defenders and get in behind as much as I can, open the space for the midfielders and keep possession once it’s in their half,’’ Bruin said.

The lead didn’t last long, as Toronto responded to Bruin’s goal by pouring on the heat. Sebastian Giovinco rattled one of his typically near-perfect free kicks off the post in the 38th minute and then Jonathan Osorio headed home the equalizer two minutes later after a nice touch pass in the box from Victor Vazquez.

But Vazquez, one of the most dangerous Toronto players, left at halftime with a leg injury. It was a huge loss for Toronto, already without striker Jozy Altidore after his foot surgery earlier in the week.

For the Sounders, switching to a 5-4-1 formation – as opposed to their usual 4-2-3-1 – had been more for attack purposes than defense, though the extra defenders did seem to clog the field and confuse the lethal Toronto side early.

“It felt like we defended for 90 minutes, but once you can get that lead it’s much nicer defending,’’ said Sounders midfielder Cristian Roldan, who had fed Eikrem the ball ahead of Bruin’s opening goal. “Will (Bruin) was massive in that way, took his first chance and scored. Once you have a lot of young guys who are committed to defending the whole game it makes your job a bit easier because you know someone will be there to cover (for) you.’’

Schmetzer had hoped going with three center backs instead of his usual two would enable fullbacks Waylon Francis and Jordan McCrary to push forward along the flanks and keep Toronto’s explosive attack a bit more honest.

It worked, as the Sounders appeared to have more pace in the first 10 minutes than in their entire 0-0 draw Saturday against Columbus.

Their scoreless stretch against Toronto included 120 minutes of regulation and overtime in the 2016 MLS Cup final before that game ended 0-0 and went to penalty kicks.

Last year, the Sounders lost 1-0 at home to Toronto in May, then dropped a 2-0 decision last December in the MLS Cup rematch.

It’s been a long five months since for Schmetzer’s crew, rocked by injuries and a quarterfinal exit in CONCACAF Champions League play. They entered Wednesday 1-4-2 in MLS and playing three games in eight days, thus Dempsey and Alonso were left home while Kim Kee-hee stayed benched.

“I would say this club is always a proud club, we always fight, we never give up,’’ Schmetzer said. “Results like this come from that mentality, that type of mindset. It is within our club. It’s been like that since Kasey Keller has been here in ’09 and that will always be there.’’

The Sounders head to Portland on Sunday with a much-stronger and rested complement of regulars. And a huge boost of confidence – perhaps having exorcised some lingering ghosts from last December’s debacle.