Bradley Wright-Phillips scores the first goal of the match. (Patrick Gorski/USA TODAY Sports)

BRIDGEVIEW, ILL. — Playing the underdog worked just fine for the Red Bulls Wednesday night.

Sixth-seeded New York pulled off a stunning upset in the knockout round of the Major League Soccer playoffs, defeating the third-seeded Chicago Fire, 4-0, in the Eastern Conference match at Toyota Park.

Bradley Wright-Phillips and Sacha Kljestan tallied first-half goals for the visitors while Daniel Royer added second-half tallies.

“I really can’t complement the boys enough,” Wright-Phillips told FS1. “It was a real professional performance.”

The Red Bulls surprised the hosts by taking advantage of two mistakes by the Chicago defense in the opening 11 minutes.

First, Wright-Phillips struck for his 99th goal in all competitions for New York in the seventh minute. He latched onto a Damien Perrinelle feed in the penalty area. Goalkeeper Matt Lampson hesitated just a bit to come off his line as BWP broke in as the English striker had an easy tap-in for a 1-0 lead.

Four minutes later, Kljestan, who had but two goals during the regular season, doubled the lead. This time an overlapping Tyler Adams crossed the ball from the right flank to a sliding Kljestan, who scored from five yards.

“He was brilliant tonight,” BWP said of the team captain.

“Playing on the road we played with aggression,” Kljestan said. “We played as though we were at home tonight.”

Royer made it 3-0 after a Sean Davis set-up in the 70th minute.

Veron, who replaced Wright-Phillips minutes earlier, put an exclamation point on the match with his goal in the 87th minute as he chipped Lampson off a breakaway.

Goalkeeper Luis Robles recorded the shutout.

“We have a lot of confidence now,” Adams said. “We’ll come out flying again.”

The Red Bulls will need to. They will host Supporters Shield champion Toronto FC either Monday or Tuesday night in the first leg of the Eastern Conference semifinal series. The second leg will be played in Toronto Sunday, Nov. 5.

“Toronto is a different tart and we’ll prepare for that,” Wright-Phillips said.

Added Kljestan: “They’re probably the best team in MLS history.”