Arsene Wenger has sanctioned a late bid to land the England international after failing to capture Radamel Falcao and Loic Remy over the past 48 hours.
The Gunners are trying to snatch Welbeck from under the noses of Tottenham, which was in advanced discussions to sign him on loan.
MORE: Beautiful people who love the beautiful game | Transfer photos
Goal understands that Arsenal want to sign Welbeck on a permanent deal but United would prefer that he join the North Londoners just for the season.
Welbeck, who trained with England at Arsenal's London Colney headquarters Monday, is on standby to undergo a medical at the center.