Kanu was left red faced prior to this afternoon's Arsenal Legends charity match, but he ended up a hero by scoring a hat-trick in a 4-2 victory over Milan Glorie.
Before the friendly kicked off, Kanu mistakenly took a place on the pitch, thinking that he was in Arsene Wenger's starting lineup.
However, the Nigerian, who spent five years at Arsenal during his playing career, was named among the substitutes' bench, and had to be led off the field by Gilberto Silva.
The 40-year-old saw the funny side, though, as he applauded the supporters, while Wenger could not hide his amusement in the dugout.
After officially entering the field of play, Kanu impressed by scoring three times, and Robert Pires rounded off the win for Arsenal Legends with a late goal of his own.
The match was in aid of The Arsenal Foundation.