Following Manchester City's demise at Everton just before the international break, United require only 13 more points from their remaining nine games to clinch a record 20th championship.
"With Manchester City coming on the scene in the last couple of years and Chelsea and Arsenal and Tottenham, you have teams vying for that top-four position," Ferguson told Sirius XM."I expected it to be really tight. But I never thought we would be 15 points clear at this stage of the season."
They might not even need 13 given City visit Old Trafford on April 8, and the feeling is Ferguson has already set his sights on eclipsing United's record 18-point winning margin from 2000.
It has given Ferguson some leeway with his selections over the Easter weekend, when United find themselves pitched into two key games in the space of 48 hours.
Following Saturday's lunchtime trip to Sunderland - which could move United 18 points clear given City are not in action until slightly later - the Red Devils must prepare for Monday's FA Cup quarter-final replay with Chelsea at Stamford Bridge.
As one of the players not being troubled by international duty, Rio Ferdinand can expect significant involvement following his controversial trip to Qatar, whilst Ryan Giggs, Nemanja Vidic and Anderson should also be fresh.
"Every coach is praying that their players come back fit," said Ferguson. "They played last Friday and they are playing tonight. Once I know later this evening how many minutes each player has played, I will start to think about my team for Saturday.
"I have to make sure I have some freshness in the team because we also have Chelsea on Monday lunchtime.
"It is a big ask for our squad and something we need to concentrate on because I need to make sure I pick the right teams."
Source: PA
Source: PA