Chris Smalling says Manchester United have Arsenal and Chelsea in their sights following their resounding victory over champions Manchester City. United are third, eight points behind leaders Chelsea, who they face on Saturday and play second placed Arsenal in their penultimate league game. Smalling scored United's fourth goal in their 4-2 derby demolition. It means he has now scored the same amount of Premier League goals this season as former teammate Danny Welbeck at Arsenal with four. Chris Smalling showed his hunger to beat a lethargic City defence to Ashley Young's free-kick . Smalling is greeted by Juan Mata following his goal in Manchester United's impressive win over their rivals . He said: 'It’s massive [to win six in a row]. I think a lot of people probably saw our fixtures as the hardest of the lot, but if you play teams like Tottenham and Liverpool and win, they’re real six-pointers. It makes a massive difference, and I think confidence comes from beating these top teams. 'We weren’t ourselves in the first 15 minutes, but we dominated from there on. 'We came in at half-time and Giggsy said it was a good show of character to come back from a goal down, but in the second half we needed to get the ball down and take a few more risks. Mata once again showed his value to the side and pointed the way with a display full of energy and poise . 'We were a bit cautious and didn’t try to play out [from the back] too much, but in the second half we really kicked on and made a print on the game. Smalling ghosted into the area unmarked to head Ashley Young's free-kick past Joe Hart on 73 minutes. Wayne Rooney leaps onto Marouane Fellaini's back after United took the lead through the big Belgian . 'I wanted to try to get a run on early; I was ready to pop up and it finished the game,' he added. 'I think today put us up another step and I think we’re on a roll; we can look up the table and not behind us. 'You could sense even from the warm-up that the atmosphere was going to be special. We lost against City earlier in the season so today was massive and I think the fans really stuck with us.' All of United's outfield players celebrate as they gave noisy neighbours Manchester City .
Chris Smalling scored as Manchester United beat rivals Manchester City .
Win sends Louis van Gaal's side four points clear of the Citizens in third .
Manchester United now sit just one point of Arsenal who occupy second .
Smalling is confident of chasing down both them and leaders Chelsea .
READ: Five things Van Gaal has done to transform United's results .