Simon Grayson says the riches of the Premier League have made it harder than ever to win promotion from the Championship.
Grayson, who managed four sides in the second tier before joining Sunderland, has witnessed the quality in the league rise at first hand as the Premier League boom trickles down.
The Black Cats will have to compete with a number of heavyweights for promotion this season, including Leeds United, Sheffield Wednesday, Aston Villa, Nottingham Forest and Middlesbrough.
He said: “Because of the nature of football, they way it is going [teams are dropping].
“The English leagues are arguably the biggest in Europe, if not the world, and the Premier League attracts the big stars and before you know it, players that would be playing regularly in the Premier League 10 years ago are having to drop down to the Championship to make a career in the game and that is making the Championship more successful and interesting and tougher to get out of.”
Grayson has won promotion for League One four times but is still looking for his first leap into the Premier League.
After leading Preston to three successive mid-table finishes despite working with one of the smallest budgets, Grayson has warned his players that in this league reputation counts for nothing.
He said: “That should be an inspiration to players that you are challenging yourself against some very talented players.
“Anyone can beat anyone on any given day in the Championship and you have to be at it, full tilt in every game and earn the right to win every football match because of the competition and the size of some clubs.
“You have former European Cup winners in this division and teams that have been around the top end of the Premier League at times.
“But the names and what they have done in the past are irrelevant. It is about the present and what you want to achieve now.”