United are eight points adrift of the Gunners who top the Premier League and David Moyes’ side may view Sunday’s clash as a must win game in order to get their season going again.
A disappointing draw in Spain against Real Sociedad in midweek will not fill United with much confidence and Arsenal’s stunning 1-0 win in Dortmund keeps their fine form going this campaign.
Bosnich knows that United cannot afford to lose but the Australian has heaped pressure on Arsenal too as this is their toughest test in the league so far this season too.
“I don’t think United can afford to lose this game,” Bosnich told talkSPORT.
“It is a massive test for Arsenal going to Old Trafford but there will be reverberations throughout the Premier League if they do manage to beat Manchester United away from home. It will really put a marker down.
“As it is at the bottom of the table when you play teams around you and they become six pointers, it is the same at the top of the table as well when you play fellow title contenders.
“It’s a real opportunity for Arsenal to take themselves well away from what is a title contender in Manchester United.”