Rafa Benitez arrives at Newcastle United with a lucrative short term survival mission, but hopes it will turn into a rewarding long term project if he can keep the Magpies out of the Championship.

Benitez has signed a three-year contract to replace Steve McClaren, who was finally put out of his misery in a telephone conversation with managing director Lee Charnley on Friday morning, at the same time as the Spaniard drove up from Liverpool to complete his paperwork.

It was only the second time McClaren had spoken to Charnley since the abject 3-1 home defeat to Bournemouth last weekend, even though the club had been publicly searching for his replacement since Saturday night.

Benitez’s arrival has excited supporters, who had given up hope of avoiding relegation if McClaren - who won just six out of his 28 matches – remained in charge.

The new boss made an early impression on his players too, cancelling their scheduled day off in order to take an impromptu training session, just a few hours after posing for pictures upon his arrival on Tyneside.

Significantly, Benitez has been appointed as manager – the first foreign one employed by Ashley - rather then head coach, but he will not stay around to see what level of control he has over recruitment if Newcastle are relegated.

Telegraph Sport understands a clause has been inserted into the Spaniard’s contract allowing him to leave in the summer if he fails to keep the club in the top flight. If he does keep them up, it is thought a manager who will earn around £2m-a-year on Tyneside will also receive a large “survival” bonus from owner Mike Ashley.

Confidence that Newcastle will avoid the drop has soared following the 55-year-old’s arrival and he will be in charge of the team when they face Leicester City on Monday night.

Intriguingly, Benitez’s first home game will be against Sunderland, the team directly above them in the table, who are managed by his bitter rival Sam Allardyce.

As someone used to competing for silverware, this is Benitez’s first relegation battle as a manager, which was something he was concerned about when first asked about the Newcastle job.

For a man who was in charge of European giants Real Madrid two months ago, there is no appeal in the prospect of facing Rotherham and Preston in the Championship next season.

It is already a stunning realignment for a manager who was working with the likes of Cristiano Ronaldo, Gareth Bale and Sergio Ramos at the Bernabeu. He will now be expected to lead the likes of Paul Dummett, Yoan Gouffran and Steven Taylor to safety in the Premier League, with only ten games remaining.

“I have the pleasure to confirm I have committed to a legendary English club, with the massive challenge of remaining part of the Premier League,” Benitez told Newcastle’s official website.

"It will be a challenge not just for me and my staff but for the players, the Club and the fans.

"All of us must push together in the same direction and with the same target in mind. This is the reason why I'm going to ask for your total support to successfully complete this task.

"Personally, it means my return to the Premier League, closer to my home and my family. I can't be happier.

"C'mon Toon Army! The club and I need your total involvement!"

That last sentence caused much hilarity on social media, but his arrival will harness the power of the club’s fan base, which had become disillusioned – not for the first time under owner Mike Ashley – and devoid of passion in recent weeks.

Credit must go to Charnley, who has helped persuade Ashley to rip up the management structure that has not given Newcastle’s managers control over recruitment, since 2008. It can only be hoped that the promises that were made to lure Benitez to Tyneside are kept, because he is unlikely to remain at the club if, in the next transfer window, they are not.

“I am very pleased to welcome Rafa Benitez to the club,” said Charnley, who apologised for the way McClaren’s had been treated while he searched for his replacement in an earlier statement. “In Rafa we have, without doubt, secured the services of one of Europe's top managers.

"He has managed some of the most successful teams at the very highest level of the game and we are proud to now have him as our manager.”

Newcastle swiftly confirmed that McClaren’s backroom staff, Paul Simpson, Alessandro Schoenmaker and Steve Black had also left the club. They have been replaced by Fabio Pecchia, Francisco de Miguel Moreno and Antonio Gomez Perez.

However, Newcastle’s treatment of McClaren drew some criticism, with Gary Lineker tweeting: “Newcastle have finally put Steve McClaren out of his misery. The running of that great football club is beyond shambolic.”

McClaren, who has behaved with dignity in extremely testing circumstances this week, released a statement through the League Manager’s Association.

“I appreciate any frustrations relating to the team’s results and the club subsequently finding itself in a battle to avoid relegation,” he said. “I remain confident, however, that we would have stayed in the Premier League with a view to building for next season.

“Whilst there has been a lot of intense speculation surrounding my position in recent days, my sole priority has been to maintain my professionalism and carry on with my work to best prepare the team.”