United go to Sunderland in the Premier League in Saturday's early kick-off before they they take on Chelsea at Stamford Bridge in the FA Cup sixth round on Easter Monday.
Ferguson, whose side have a 15-point lead over rivals Manchester City in the title race, is aware that with two big games in quick succession, he will have to freshen his side up and could even name two completely different starting XIs for each game.
"Freshness is the name of the game now as we come towards the end of the season and the intensity of vital games coming in quick succession," he told the Daily Mirror.
"My role becomes even more important in selecting the right teams, with freshness the operative quality. It's not necessarily putting out your best team, it's picking the freshest."
The United boss has already confirmed several of his international stars, who have been away with their countries during the domestic break, will return to the UK on private jets.
He added: "This will be a real problem when the players come back at the end of the international break after playing two games involving long flights, particularly with Chicharito in Mexico and Shinji Kagawa with Japan.
"In fact, we're making arrangements for some players to fly home by privately hired jet after their matches, to make sure they get home as quickly and smoothly as possible.
"Tiredness is a great leveller but we will do our utmost to make sure we field the freshest possible teams. Private planes are going to cost the club an awful lot of money, but it is something we feel we have to do."