Arsenal beat the deadline to bring in Welbeck
Many eyes were on the Emirates ahead of deadline day, with many suggesting their frontline was in dire need of reinforcements after it emerged Olivier Giroud would be out until the new year.
And with United signing Monaco striker Radamel Falcao in a stunning loan switch, Louis van Gaal has allowed Welbeck - who was rumoured to be interesting Arsenal's bitter north-London rival Tottenham - to join a direct competitor for a top-four place.
Welbeck, still only 23, scored 37 goals in 121 appearances for his boyhood club and follows Javier Hernandez, who joined Real Madrid on loan, in heading for the Old Trafford exit door on Monday.
He has also gained 26 England caps, finding the net on eight occasions.