Sir Alex Ferguson believes United are building up a head of steam in the Premier League title race - even if they will have to cope without their match-winner against Arsenal after Christmas. Ji-sung Park headed the Reds to the top of the league last night but after Boxing Day's match against Sunderland he is off to Qatar for the 2011 event with South Korea. The midfielder won't return until February. But he has certainly put United into a strong festive season position. Reds boss Fergie saluted his defence after they kept the Gunners out in the 1-0 success. We had to play well. In these major games you want to perform and we did perform particularly in the first half, said Sir Alex. You have to play well against Arsenal and recently we have been playing well. It was another good performance. In the second half Arsenal came into it a bit but didn't make any really chances. But they pegged us back and we should have done better on the counter attack. We had some good chances then. We have a difficult game against Chelsea on Sunday and that is going to be a very important game now. It is massive. It's a big, big game for United and we could go a long way to establishing the lead at the top of the table. We are starting to get there. Our form is improving and with our back four performing like that we will have a good chance. They were fantastic. They were magnificent and that foundation always gives us a great chance. 1-0 wins can win you leagues. Park's winner came in the 40th minute but a Wayne Rooney
missed penalty after 73 minutes heightened the tension. It was an unusual penalty. Normally Wayne will keep them down, added Ferguson. I have never known him hit one over the bar. It gave Arsenal a bit of impetus. But we defended very well. Arsenal picked up four yellow cards in the match but United players avoided a caution in what was a high octane encounter. It wasn't too feisty, added the United manager. The referee (Howard Webb) was very lenient in the first half but in the second he had to produce yellow cards at the right time. You must expect two top teams are going to be competing very, very strongly in a game like that. Park's record against Arsenal is very good. He has been in fantastic form the lad but, unfortunately, we will lose him after December 26 to the Asian Cup. We will miss him for seven matches. That is disappointing. Patrice Evra, who prior to kick-off had stoked up the atmosphere with his claim that Arsenal were an Academy team' added: We are powerful, everybody was focused and worked hard with a great spirit. We got the result we deserved. It is never easy against Arsenal because they are a great side and they put pressure on us. But we stayed strong, everyone defended together and we did not concede. We have got Chelsea coming up now, so let's play with the same spirit, then we can win many games this season.