However, Bosnich is confident that the defeat won't badly affect United's title bid.
"It's marathon not a sprint. There is a long way to go, I don't want people hitting the panic button yet," he said.
"You look back to 1995 when we at Villa played them on the opening day of the season. They had just let go of [Andrei] Kanchelskis, Mark Hughes and Paul Ince and we beat them 3-1. That was the famous night Alan Hansen said you won't win anything kids - and they went on to win the double."
Bosnich enjoyed two spells at Old Trafford during his career.