– Minnesota United’s season-opening 3-1 victory over Portland on Sunday was an example of the new math, where 2 + 2 equaled its three goals.

“Two and two,” midfielder Ethan Finlay said. “Two assists for me and two goals for him.”

“Him” is veteran teammate Kevin Molino, who scored twice, while newcomer Luis Amarilla scored the first of many promised during a second half that delivered all the game’s four goals.

United coach Adrian Heath has called for Finlay and Molino to again become the players they once were, two years after each underwent knee surgery for a torn anterior cruciate ligament.

Sunday, Finlay contributed to all three Loons goals and Molino scored the night’s first and last goals. Their players weathered a slow start and proved themselves resilient.

“I thought we were worthy winners in the end,” Heath said.

Molino made it 1-0 in the 51st minute, but that lead was brief. Loons defender Ike Opara was penalized for bringing down Felipe Mora at the penalty area’s corner, and Timbers captain Diego Valeri converted the kick and tied the score in the 56th minute.

Moments later, Portland keeper Steve Clark’s reaching save stopped Robin Lod’s shot from 10 yards out — and yet United persisted.

“It’s a real sign of maturity to go up 1-0, give up a goal, a penalty kick, on the road and respond the way we did,” Finlay said. “I’m proud of the guys. It’s a sign of maturity and experience.”

Amarilla’s winner came in the 76th minute on the same kind of crossing pass from Finlay — down the right sideline — that led to Molino’s persistent first goal.

“His energy levels were terrific,” he said of Finlay “but that’s what we know we’ve got with Ethan.”

Amarilla’s header on the far post directed past Clark on the short side, the first goal in MLS play for an attacker who audaciously told Heath he would score 25 goals this season.

One down, only 24 to go.

“I did say that to him,” Heath said.

For now, though, Molino has scored twice the goals Amarilla has. He got his brace soon after by converting Finlay’s overhead flick out of four converging defenders with a patient right-footed volley that eluded Clark.

“I’m pleased for Kevin because he’s worked really hard this preseason,” Heath said. “We’re trying to get him back thinking about scoring goals.”

Finlay called Molino’s second goal “clinical” after Finlay himself improvised to get the ball Molino’s way.

“The ball was sitting too high for me to strike, so I was just trying to get it back across my body,” Finlay said. “I don’t know how many will buy that. But I’ll take it either way.”

Amarilla has promised 25 goals. Molino was asked if he would like to declare his own objective.

“Looking for double figures,” he said. “I’m going to put myself under a significant amount of pressure and through the season, I’m going to get there.”

Portland didn’t play its first home game until June last season while Providence Park was remodeled. Now the Timbers are 0-1 there, having lost to Minnesota at home for the first time in the Loons’ four MLS seasons.

“Not the way we wanted to start the season,” Portland coach Giovanni Savarese said. “… To give up two goals in the second half after we were 1-1, it’s not what we want. Especially after what we showed the first half, when we were completely dominant.”