The Dutchman all but confirmed the Reds' place in the tournament's final in Kiev on May 26 when he headed home from close range in the first half of a 4-2 defeat at Stadio Olimpico.
And he reacted by running straight toward the bench before embracing the club's head of fitness and conditioning while wearing a trademark grin.
Asked about the moment after the match, Wijnaldum said: "We already had an agreement a few games ago that I would run to him if I scored but it didn’t happen.
"He said a few times that I’d score but then he forgot.