Chelsea boss Roberto di Matteo isn't surprised by Arsenal's form this season.

Di Matteo knows his side face a real test today against an Arsenal outfit who are going well despite losing Robin van Persie to Manchester United.

The Gunners are fifth and - like Chelsea - undefeated.

Di Matteo said: "I said at the start of the season Arsenal would be challenging for the league.

"I'm not sure anyone believed me, but that's the way I saw it and I haven't changed my mind. They have signed some very good, interesting players.

"But I don't think they are playing differently.

"The personnel has changed, but the philosophy hasn't changed.

"Arsene Wenger has done a fantastic job."