Manchester United boss Sir Alex Ferguson says managers need instant success to stay in the job.

Ferguson accepts times have changed from his arrival at Old Trafford, where he was into his fourth year before he finally managed to secure some silverware.

But the key to success remains the same. You have to win.

"The only route for any manager is success," he said. "It's a results industry so winning matches is important.

"It's a different game from when I started. There was less pressure.

"The world has changed. The press has changed. But I always felt I needed to win games.

"That's what you're in it for. It doesn't matter whether you're managing Port Vale, Liverpool or Manchester United, you have to get results."