After a tricky pre-season campaign, dominated by talk of Wayne Rooney's future, the clock is ticking down to David Moyes' first competitive game in charge.
That Saturday's trip to Swansea is followed immediately by matches against Chelsea and Liverpool, with Manchester City to come only two games later, Moyes is facing up to the most difficult of starts to his Old Trafford career.
Keown knows he has the ability to make a success of the job. But it is doubtful anyone could emulate the sustained trophy gathering that became such a hallmark of Ferguson's tenure.
And that, according to the former Arsenal man, will give all United's rivals a little bit of hope.
Speaking at the 2013 FA and McDonald's Community Awards, Keown said: "David Moyes is an outstanding manager but he is not Alex Ferguson. If you are a competitor, you see a chink of light.
"Before you felt you were playing as much against Sir Alex as you were Manchester United because of his status in the game."
Keown is as interested to see the reaction inside the United dressing room and the response from Chelsea, Manchester City and Arsenal.
"The biggest thing for me is how will it affect the Manchester United players," said Keown. "They have worked with Sir Alex for a lot of years. He would have met their needs, re-assured individuals, found the necessary words to motivate them when he needed to.
"He isn't going to be there now and there is uncertainty in any workplace when a new boss comes in. If they get the wrong results, they might end up leaving a big gap which they are not able to close."