Owusu-Abeyie had been on the pitch just eight minutes, but his cool finish put the Blues ahead and on the way to their unforgettable 4-1 win over Southampton.
On loan from Spartak Moscow, Owusu-Abeyie then opened up the hosts with his electric pace as Pompey tore Southampton apart on the break in the final 25 minutes to book a place in the last eight of the FA Cup.
"I felt good today and I was pleased with my finish," he told the club's website.
"You have to think quickly when the ball comes to you in the box. I saw a little gap in the far corner and managed to put it in.
"There was a lot of space on the pitch out there when I came on and that was perfect for counter-attacking. That's how we scored all our goals."