Manchester United  striker Wayne Rooney  has insisted that the Red Devils must stay focused to reclaim the Premier League title from Manchester City  despite their 15-point lead at the top of the table.United host City on Monday night having won seven top-flight matches in a row and Rooney is keen to ensure they avoid slip-ups that could cause a domino effect."You have to stay focused," he said. "You have to make sure that we keep doing our job and keep our concentration. "One bad game and everything could fall and so we go out and play each game with a positive attitude."Rooney admitted that the manner in which United conceded the title last season stung but claims the 19-time champions do not require any extra motivation to compete for silverware."To lose the league in the last second was a bad feeling but when you’re at a club like United, you have to be full of motivation and desire to win every year," he explained."That comes from the manager and all the players are aware of that. The club and the players have to be full of that desire and that’s why the club has been so successful."For that reason, the England international says that his well-known competitive streak - though he has not been sent off at club level since 2009 - remains a vital component of his game."I have always been like that, whether I'm on the golf course, the computer, and the football pitch," Rooney continued. "I have always wanted to win and it comes from how I was brought up. "If I was losing against my mates I could lose my cool if things went against me and now I am a pro that is the same. You need to be like that I think."Rooney has now established himself as one of the world's finest forwards but revealed that he returned home for a kickabout with his friends after his first Premier League goal against Arsenal in 2002."We went and played in the garages nearby," he recalled. "We just shot at each other all night. No one treated me any differently. A few congratulated me about the goal but otherwise no one really made a fuss."Wayne Rooney was speaking at a Nike FC247 shoot where he tried out the Nike Bomba Finale II, a boot designed for astroturf football.