With their UEFA Champions League last-16 second leg clash against Real Madrid looming next Tuesday, Ferguson knows how important it is to get the balance right as he chases success on three fronts.
But for those who miss out, the United boss can point to a very real example to prove it does not necessarily mean they will not have an impact with the Red Devils.
"In 1999 I left Paul Scholes out of the quarter-final against Inter yet he was the one who scored the goal that got us through," Ferguson told MUTV.
"I left him out of the semi-final because I couldn't risk him and Roy Keane together as they were both on yellow cards. He accepted it graciously, came on, got booked and missed the final anyway.
"What did he do? He didn't let it affect him. He went on to become one of the greatest players this club has ever had.
"The players sense it could be a big year for them.
"But at this club, in this situation, anything can happen on the run-in. Players can all of a sudden find themselves playing in a final or an important league game because that is the kind of squad I have.
"It is very difficult to rotate the squad at the moment. They all wanted to play against Real Madrid and there were a lot of disappointed players.
"That was fantastic. It is a measure of their own confidence in themselves.
"But we had a chat. I said 'look, don't think for a minute losing a game for Manchester United is a trivial matter'. It is a serious matter."
The first guide to Ferguson's thinking will come with his team selection for Saturday's Premier League encounter with Norwich.
And with a run of four successive home games, United can heighten their chances of repeating their epic 1999 Treble, especially as the Old Trafford pitch, which Ferguson said had "collapsed" post-Christmas, has been brought back to life.
"The pitch has improved a tremendous amount," he said.
"By the time we play Norwich I expect it will be back to normal so hopefully we can take advantage."