Manchester United boss Sir Alex Ferguson believes the key to defeating Arsenal is to nullify the threat of star striker Robin van Persie - a player the Scottish coach considered signing.

33065 - Arsenal a one-man team - Fergie

United and Arsenal lock horns in the Premier League at Emirates Stadium on Sunday, and Ferguson has pinpointed the quality of Van Persie, comparing the Dutchman to the likes of Barcelona's Lionel Messi and Real Madrid's Cristiano Ronaldo.

Ferguson said in the Guardian: "It has become a case of stop Van Persie and you stop Arsenal. His form has been fantastic this season and his goal record speaks for itself. I hope he doesn't add to it this weekend.

"Arsenal have come to rely on him but I think you could say exactly the same thing about Barcelona. If you can stop Messi they are not the same team, and if you can stop Ronaldo then Real Madrid are not the same team.

"The very best teams always seem to have a player who can make a difference. Manchester City have David Silva, and for many years when he was at his peak Didier Drogba was a matchwinner for Chelsea."

Van Persie, who joined the Gunners from Feyenoord for £2.75 million in 2004, has been in prolific goalscoring form for Arsenal this season, scoring 18 goals in 21 Premier League games. And Ferguson has revealed the Red Devils were keen on the striker, whose contract expires in 2013, before Arsenal moved to acquire his services.

"I remember going to see Van Persie play for Feyenoord reserves, way, way back. We were definitely interested, but the day we went to see him he didn't play the full game. He was either sent off or he walked off, I can't remember which.

"We ended up leaving it, we didn't make a move for him. I don't think we saw enough of him to make a decision, whereas Arsenal were much closer to the situation at the time and they eventually got themselves a terrific player."