Robin van Persie insists he is yet to hit peak form despite making a sparkling start to his Manchester United career. Van Persie has scored 13 goals in 19 appearances for United since his £24m move from Arsenal, but the Dutch star admitted he is not completely happy with his performances. The 29-year-old has helped United to the top of the Premier League, but he believes he can still deliver more goals and assists, starting in Sunday\'s showdown with title rivals Manchester City at the Etihad Stadium. \"When you are wanted by everyone it gives you wings,\" Van Persie told MUTV. \"I am happy here and everyone looks very happy to have me here. But I am not satisfied. If you look at the stats, 13 goals in 19 games, it is OK. But I want better and more. I want more goals, more assists. I want to go for everything that it is possible this year.\" United hold a three-point advantage over second placed City, but their bitter rivals will replace them on top of the table with a victory on Sunday as they have a superior goal difference. And Van Persie acknowledges United\'s poor defending this season has to improve if they are to keep ahead in the title race and also thrive in the UEFA Champions League. The way he gets us ready for the games is different class. Robin van Persie, Manchester United striker on Sir Alex Ferguson \"I do (accept United have not been playing at their best). But I just come back to the winning part,\" Van Persie said. We have been winning. We are first in the league, first in the Champions League. Everyone would have signed for that a couple of months ago. Up to now we can accept it. It is good. Now we have to improve. If you just take away a couple of the goals we gave away in away games, we would have made life easier for ourselves.\" After several years playing for an Arsenal side that struggled to challenge for major honours, Van Persie is just relishing the chance to compete for silverware. He has no doubts that United manager Alex Ferguson is the key to their success and paid tribute to the Scot\'s ability to inspire his players with his team talks. \"The way he gets us ready for the games is different class,\" Van Persie said. \"Those speeches are very important for every single one of us. The things he says, when he says them, before the match, during the match and after it. It is very direct. It is all spot on and very honest. I love that. We Dutch people like to be straight and honest and he tells you how it is. \"If it is good, it is good. If it is not good enough he will tell you, so you have to improve straight away. That is what I like. No one can play 10 games and play well in all 10. You always have a couple of games where it is not going so well. You have to deal with that.\" From FIFA