After Wayne Rooney went against his manager's comments about an ankle injury dogging him all season, claiming that he had no such problem, he has given Ferguson a dilemma.
Whether Ferguson rests his out-of-form striker, maintaining his stance that he is not fully fit, or plays him against West Brom, the decision will be heavily scrutinised.
I think he will say to Rooney that if he has no problem with his ankle, go out on to the pitch and prove it. In doing so he will deflect the attention back on to Rooney. If he thrives, he has got his star man back, and if he struggles then he is vindicated.
It's clear that Rooney's head is still not right, and with his loss of form coming at a time when his contract is up at the end of next season, he is suddenly in a precarious position.
There has been talk about interest from Real Madrid recently, but there is just as much chance of that being stirred by agents as having any basis in fact. Besides, after the way he has played since the end of last season, why would he be wanted at the Bernabeu?
Rooney needs to think very carefully about his next move. To come out and openly defy Ferguson, after all the support he has received through such a difficult time in both his personal and professional life, means he is walking a very fine line.
Everyone talks about the infamous 'hairdryer' treatment players suffer when they upset him, but when he's really had enough then his response is a lot more emphatic. One day, you're a Manchester United player. The next day, you're gone.