CHESTER, Pa. — As Roland Alberg sprinted from behind the goal to the sideline, took off his pinnie and prepared to enter the game, a roar erupted from the Sons of Ben.

The Philadelphia Union fans know what other teams around the league have been quickly finding out: the Dutch midfielder is instant offense.

Alberg proved it again Saturday night, scoring a stunning second-half goal two minutes after coming in and adding an assist in stoppage time to lift the Union to a big 2-0 victory over Sporting Kansas City.

“He’s a very valuable player to our team and shows we have a deep squad,” Union head coach Jim Curtin said. “I can’t say enough about how well he’s played in any role — as a starter for us, he’s won a bunch of games; and his role off the bench, he’s won us some games now too. He’s a special player who makes plays and you need playmakers in this league.”

Although he’s been in and out of the starting lineup throughout his first MLS season, Alberg has indeed proved to be a dynamic presence whenever he’s on the field. He now has nine goals in 925 minutes, the best goals-per-minute average in the league.

Against SKC, Alberg almost scored again in the 84th minute on a great ball from fellow sub Charlie Davies. And three minutes after that, Alberg drew the foul that got Roger Espinoza shown the second red card of the game for SKC.

The Dutchman then took advantage of that two-man edge with a clever pass that sprung Tranquillo Barnetta for a stoppage-time goal, icing the victory that snapped Philly’s two-game home losing streak.

“My first thing is I have to show it every training, and then it’s the coach’s decision,” Alberg said. “If he uses me as a sub, I’ll do 100 percent my best. And if it’s as a starter, it’s the same thing for me. Of course every player wants to play as a starter. But it’s a long season. Playoffs, they are coming. So I’m patient.”

The playoffs could certainly be on the horizon for the Union, who set a franchise record for home victories with eight.

And Alberg, who heard his name chanted by the fans as he exited the field, is a big reason why Philly jumped into third place in the East with Saturday’s win — even if he no longer starts.

“Roland does a great job; he has a knack for goal,” Curtin said. “He scores. … He has a special quality.

“You do have to give him credit — he could have put his head down. I think he’s actually worked harder in games and in training, especially on the defensive side. Everything he touches tends to lead to a goal or is darn close to a goal.”