The midfielder poked home the equalizer in the 87th minute Wednesday after wearing the goat horns early as the Vancouver Whitecaps tied FC Edmonton 1-1 in the first leg of their Amway Canadian Championship semifinal.
Koffie gifted the visitors a 1-0 lead in the fourth minute when he was stripped of the ball in front of the Vancouver goal by Tomi Ameobi, who moved in alone and beat Paolo Tornaghi with a low shot.
"It's part of the game," Koffie said of his gaffe. "Mistakes happen here and there."
After the Whitecaps wasted a number of chances to draw level in the second half, Koffie made amends late to set up an intriguing second leg in Edmonton next week.
"I want to be a team that tries to pass the ball and play," said Vancouver head coach Carl Robinson. "Because I want to do that we will make mistakes.
"I think (Koffie) grew into the game and obviously he answered nicely."
The Whitecaps actually had an opportunity to win it in stoppage time, but second-half substitute Robert Earnshaw's effort hit the side netting.
"I'm delighted we got the goal in the end," said Robinson. "I think we deserved something out of the game."
The Whitecaps fielded a younger lineup without much Major League Soccer experience against their opponents from the second-tier NASL, with Koffie as one of the few veterans in the starting 11, and looked nervous early on against a physical Edmonton side that will take a valuable away goal into the rematch.
"The guys weathered the storm," said Edmonton head coach Colin Miller. "As you would imagine it's a very, very talented Whitecaps' group. Whoever plays for the Whitecaps has got real quality.
"Absolutely ecstatic with the attitude. There were some fantastic performances. Very proud of our team tonight."
Wednesday's match was originally scheduled to be the second leg of the two-game, total-goals tie, but last week's fixture in Edmonton was postponed until May 20 after a spring snowstorm blanketed the city.
Neither club has ever hoisted the Voyageurs Cup and the winner of the tie will face the Montreal Impact in the national final with a spot in the 2016-17 CONCACAF Champions League on the line. Montreal lost 3-2 to Toronto FC in the second leg of the other semi earlier Wednesday, but advanced on a 3-3 aggregate score thanks to the away goals rule.
Vancouver has already qualified for the 2015-16 Champions League after finishing as the top Canadian club in MLS last season.
The Whitecaps seemed stunned after going down early and were second best for much of the opening 45 minutes. But they came out with more intensity in the second half, with Edmonton goalkeeper Matt Van Oekel making great saves on Erik Hurtado in the 49th minute and David Mattocks in the 58th.
Hurtado then looked certain to score in the 66th, but his rushed shot sliced harmlessly wide before Koffie finally struck late to cancel out his earlier error.
"I think we came out to win this game, but sometimes it doesn't go your way," said Koffie. "We take the positives out of this game and do what we have to do next week."
Note: Vancouver hosts the Seattle Sounders in MLS play on Saturday. ... Whitecaps defender Sam Adekugbe limped off in the first half with what appeared to be an injury to his right leg. ... Tornaghi made his first start for Vancouver after nearly 50 competitive games on the bench behind No. 1 'keeper David Ousted. ... Edmonton beat the Ottawa Fury 6-2 on aggregate to advance to this round of the competition.
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