The incident happened in Arbourthorne Road, Arbourthorne, at 9.25am yesterday when the man was attacked while returning to his Ford Transit van.
The keys were stolen and offenders drove off in the van.
This was just one of several serious crimes in the south eastern part of the city over the last 24 hours.
An armed raider threatened someone with a knife and demanded they hand over their bag in Wragg Road in Wybourn at 5pm yesterday.
The victim managed to get away unharmed.
Burglars stole a purse from a home in Smelterwood Crescent, Stradbroke, at 2.20am on Sunday.
Electrical items were taken from a property in Payler Close, Manor, sometime between 8.30pm and 9pm on Monday.
Golfing equipment and other unnamed items were stolen from a vehicle parked on Moorthopre Dell in Owlthorpe, between 12.30am and 7.10am on Monday.
Thieves stole a Honda motorbike from East Bank Road, Arbourthorne, on Monday at 11.10am.
Contact police with information on 101.