Van Persie struck in the final minute to seal a 2-0 win for West Brom before lifting his shirt to reveal the message: 'rip tchuna we will never forget you'.
It was confirmed the message related to a close friend of the Dutchman, who died on Friday night.
Sir Alex Ferguson responded to van Persie's latest goal by saying: "He is a fantastic player. He came on and changed the game for us.
"Every time the ball came up to him he got hold of it and turned on them.
"They were having to go back to their box all the time and he has done well."