Wayne Rooney scored a hat trick as champion Manchester United humiliated Arsenal with an 8-2 win on Sunday, the Gunners' heaviest defeat under Arsene Wenger.

Having seen cross-city rival Manchester City thrash Tottenham 5-1 earlier in the day, United responded in style with Ashley Young, Danny Welbeck, Nani and Ji-Sung Park joining Rooney on the scoresheet.

Rooney scored two free-kicks and a penalty, while Theo Walcott and Robin van Persie replied for a makeshift Arsenal side.

Van Persie had a penalty saved in the first half when Arsenal was trailing 1-0.

United is top of the Premier League with a 100 percent record, while Arsenal has only one point and has had a player sent off in each of its three games after Carl Jenkinson saw red against United.