Manchester United manager David Moyes said his team had secured “a big result” after beating Arsenal 1-0 at Old Trafford to move within five points of them.
Robin van Persie scored the only goal of the game before half-time to sink his old club, and Moyes said: “Arsenal have been in terrific form this season, and we had to play well ourselves today to get the result.
“I thought we started the game well and we were very good in the opening 20 to 30 minutes. And I thought, in the end, our whole determination of effort, commitment and good play helped us in the second half when we were under more pressure.”
The manager said he believed the Premier League title would be a close call this season, and added: “I don't think anyone's going to run away with it. I think there are a lot of ups and downs -- it's a close-run league this year.
“I think there will be a few shocks, and we've think we've had one or two at the early part of the season, but I'm pleased we've been able to show a little bit more consistency and a bit more momentum. Let's hope we continue that.
"Manchester United were champions last year and there's a lot of people written them off very quickly, which is fine -- but hopefully, come the end of the season, we will not be too far away from it.
"It's another step in the right direction for us. We have got a lot of big steps to take here. It is going to take a while for me to get it all the way I'd like it to be.
He hailed Van Persie's key contribution, saying: "Great players score great goals in big games, and he is a great player. I have got to say, his sidekick [Wayne Rooney] played great as well: the two of them were fantastic.
"Wayne made it [the goal] and Robin scored it. I always hoped that Robin would show that, and he has been great since I came here. Wayne's energy and the way he worked and some of the stuff he did was magnificent."
Rooney praised this side's performance after his corner set up Van Persie for the winner.
“We knew we'd have to win today at all costs,” man of the match Rooney told Sky Sports 1. “I think we defended really well, and thankfully Robin got the three points and we got the three points. I think it was a great effort from everyone.”
Chelsea's home draw on Saturday was followed within 24 hours by shock defeats for Tottenham and Manchester City, meaning United have now closed to within five points of leaders Arsenal, who suffered their first league defeat since the opening day of the season.
Rooney added: “We knew we couldn't afford to lose today and we couldn't let Arsenal get 11 points ahead of us. We knew a victory would put us right back in there, and we're in a good position.
“We worked on free-kicks and corners as Arsenal have a lot of smaller players in the team and that could give us the opportunity to get a goal, and thankfully it's paid off."
The Red Devils have won five of the last six games and are unbeaten in their last nine matches in all competitions.
Rooney said: “It gives us a massive lift. It's a great weekend for us going into the international games. We've got a big push then until the New Year, and it's our aim to still be up there."
Disappointed Arsenal boss Arsene Wenger said: "To sum it up, we conceded the goal on a set-piece and that made the difference.
"In the first half we were too nervous and lost too many balls, and in fact the corner comes from one of those balls.
"In the second half we were more composed and had a real go and played our usual game and were very, very close many times to score -- but it didn't happen.
"We have to digest that and come back after the international break and in a strong way. But the heart was in the game and the desire was there, maybe a bit too much in the first half."
Information from the Press Association was used in this report.