( CNN ) -- Wayne Rooney scored a hat-trick as champions Manchester United retained their 100 % English Premier League record this season with a remarkable 8-2 thumping of injury-hit Arsenal at Old Trafford . United dominated the Gunners who suffered their worst ever Premier League defeat . With Manchester City winning 5-1 at Tottenham also on Sunday , it proved a superb day for the two Manchester clubs , who are level at the top with a maximum nine points from their three games . What now for Arsenal and Fabregas ? In contrast , north London rivals Tottenham and Arsenal are struggling at the other end of the table , with Tottenham at the bottom without a point and Arsenal fourth from bottom with just one point . Arsenal , who sold star players Cesc Fabregas and Samir Nasri this month , were always struggling to cope with the home side once Danny Welbeck headed United into the lead following hesitancy in the defense . And Arsenal then wasted a golden chance to level when captain Robin Van Persie 's penalty was saved by United keeper David De Gea after Jonny Evans pulled back Theo Walcott . United soon made them pay when Ashley Young curled home a superb second before Rooney 's brilliant free-kick made it 3-0 . Walcott pulled a goal back for Arsenal just before half-time from an acute angle , but United restored their advantage with another trademark Rooney free-kick in the 64th minute . By now , United were running riot , and Nani made it 5-1 after being left free in the penalty area to clip the ball into the net . Substitute Park Ji-Sung added a sixth before Van Persie scored from close range to make it 6-2 . Arsenal then had defender Carl Jenkinson sent off for a second yellow card -- meaning the club have had a player dismissed in each of their first three matches . And soon after , Rooney completed his hat-trick from the penalty spot after Walcott 's foul on Nani . The humiliation was completed when Young matched his first-half strike with another superb effort in injury time . The defeat , the first time Arsenal had conceded eight goals in a league game since 1896 , increased the pressure on manager Arsene Wenger , with new signings expected to arrive before the deadline for trades on Wednesday . `` Of course it hurts , it 's humiliating , but you could see that we had not recovered physically in the second half from Wednesday night 's win over Udinese , '' Wenger told the official Arsenal website . `` We were short in some areas , that is for sure . They have class and they punished us . It was 3-1 at half-time and I think that was harsh against us . `` We missed a penalty , we had a chance to get back to 3-2 . We tried desperately to get back but we opened ourselves up and were punished . Their finishing was great today , '' added the Frenchman . United 's performance was matched by the dazzling display of big-spending rivals Manchester City , with Bosnian striker Edin Dzeko scoring four goals in their rout of Tottenham at White Hart Lane . With Frenchman Nasri in fine form on his debut following his move from Arsenal , City were too strong for Spurs , and they went ahead in the 34th minute when Dzeko scored from Nasri 's cross . And the duo combined again seven minutes later when Dzeko scored with a clever back-header from Nasri 's cross . Dzeko completed his hat-trick early in the second half when he tapped in Yaya Toure 's cutback . The home side pulled a goal back when Younes Kaboul headed in Rafael van der Vaart 's corner . But Sergio Aguero soon restored the three-goal advantage with a brilliant drive from outside the penalty area . And Dzeko curled home his fourth and Manchester City 's fifth in injury time . The result leaves Harry Redknapp 's side without a point along with Blackburn and West Bromwich Albion , who suffered their third straight defeat 1-0 at home to Stoke Sunday . In Sunday 's other Premier League match , Newcastle beat Fulham 2-1 at home with two goals from striker Leon Best .
Wayne Rooney scores a hat-trick as Manchester United thrash Arsenal 8-2 . It is the first time Arsenal have conceded eight goals in a league game since 1896 . United are level at the top with Manchester City , who hammer Tottenham 5-1 .