Manchester United star Wayne Rooney revealed the Premier League champions focused on Arsenal's smaller players during their 1-0 victory over the Gunners at Old Trafford.
The former Arsenal skipper Robin van Persie headed the ball into the net, which came from Rooney's corner in the first half. The Dutchman's goal against the league leaders was the difference between the two sides as United sealed three points at home.
The result has seen David Moyes register his first win as United manager against the title contenders since replacing Sir Alex Ferguson in the summer. Rooney admitted that his side worked on set pieces and is delighted their gamble paid off against the north London club.
"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," Rooney told Sky Sports.
The weekend league fixtures saw Manchester City and Tottenham Hotspur suffer defeats while Chelsea scored a late equaliser to avoid defeat at home against West Bromwich Albion. With United's latest victory over Arsenal, it has seen them extend their unbeaten run to nine games in all competitions.
United are fifth in the league table with 20 points from 11 games, trailing league leaders Arsenal by five points and a point behind fourth place Chelsea. Rooney believes a victory against Arsenal will give them a much needed boost as they target to be on top of the table in January.
"It gives us a massive lift. It's a great weekend for us going into the international games and we can all go off and play for our country and then come back. We've got a big push then until the New Year and it's our aim to still be up there," the striker said.
"We knew we'd have to win today at all costs. We defended really well and thankfully we got the three points, it was a great effort from everyone."
"We knew we couldn't afford to lose today and we couldn't let Arsenal get 11 points ahead of us. With the other results today and yesterday, we knew a victory would put us right back in there and we're in a good position," Rooney concluded.