Redknapp made seven changes for the third-round tie and Crouch emerged as the prime beneficiary as his predatory strikes took his season's tally to five on only his third start of the season.

The 6ft 7in England striker opened the scoring in the 14th minute when he dispatched Gareth Bale's deep cross with a fine volley and then added two more late on to seal an emphatic victory.

Jermain Defoe and substitute Robbie Keane were also on target and, with Roman Pavlyuchenko waiting in the wings, there is no denying the embarrassment of striking riches at Redknapp's disposal.

"It was a good hat-trick from Crouchie and good to see Robbie and Jermain get one each as well," said Redknapp.

"Pavlyuchenko was injured, otherwise he might have scored and made it even harder for me. It's a nice problem to have.

"It was good to get (central defender) Michael Dawson back playing again.

"He's been out for a long time with his Achilles injury and a few weeks back we wondered when he was ever going to play."

After Crouch's early opener, Defoe effectively finished Preston off with a header seven minutes before half-time but there were plenty more goals to come.

With 13 minutes remaining, Crouch tapped home Aaron Lennon's low cross but Spurs were given several scares by Alan Irvine's high-flying Coca-Cola Championship outfit.

North End lacked nothing in spirit, and pulled a goal back in the 83rd minute through substitute Chris Brown.

However, Keane added a fourth for Spurs with three minutes remaining with a fierce driven shot and Crouch completed his treble with a cheeky back-heel in injury-time.

Redknapp has transformed Spurs since his appointment at White Hart Lane last October.

"Nobody wants to lose and I thought we might well have lost this one last season," he said.

"Everyone wants to go to Wembley and you could see that with Liverpool putting in Jamie Carragher and Javier Mascherano against Leeds last night.

"We've moved on a lot in the last year and I thought we looked sharp and that every time we went forward we could open them up."

The only negative for Redknapp was a nasty ankle injury which forced Giovani dos Santos off in the early exchanges.

Irvine could hardly fault his players for effort but admitted the gulf in class between the sides was characterised by the finishing on display.

Irvine said: "I think the scoreline is unfair because anyone looking at the result will think we have been absolutely battered.

"But it wasn't like that. There were two things that were crucial - the finishing and giving the ball away cheaply with the quality of the players they have got.

"They will hurt you and there are some harsh lessons for us to learn.

"We need to be more clinical but Spurs have an outstanding choice of strikers.

"Two of them are England centre-forwards and the other one is a Republic of Ireland international.

"Whether Spurs can break into the top four I don't know, but they will certainly be there or thereabouts.

"They have got a very good squad and a very good manager in Harry."