Manchester United's Wayne Rooney reacts after their English Premier League soccer match against Arsenal at Old Trafford in Manchester, northern England, Aug 28, 2011. [Photo/Agencies]

The scoreboard is seen after the English Premier League soccer match between Manchester United and Arsenal at Old Trafford in Manchester, northern England, Aug 28, 2011. [Photo/Agencies]

LONDON - Manchester United and Manchester City left their tortured opponents and the English Premier League in no doubt they are the teams to beat this season after hugely confident demolitions of Arsenal and Tottenham Hotspur on Sunday.

Champions United battered a depleted Arsenal 8-2 at home thanks in part to a Wayne Rooney hat-trick and City striker Edin Dzeko scored four in their 5-1 away rout of a shell-shocked Spurs.

Danny Welbeck, Ashley Young, Nani and Park Ji-sung were also on the scoresheet at Old Trafford with Arsenal netting through Theo Walcott and Robin van Persie before Carl Jenkinson was sent off in a remarkable game.

The Manchester duo stormed to the top of the table with their third wins out of three after rivals Chelsea and Liverpool, now two points back, had hit the summit on Saturday.

In contrast, north London's beleaguered Arsenal and Spurs sit towards the bottom after failing to win in the league this term.