Newcastle manager Rafael Benitez must be given money to improve the team before their Premier League return next season, says club legend Alan Shearer.
Benitez spent over £50m last summer after relegation, but Shearer says there is a risk of losing the Spaniard if he is not backed financially.
"I would think giving him transfer funds would be key to keeping hold of him," said the Magpies' record scorer.
Newcastle secured promotion with a 4-1 home win over Preston on Monday.
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Speaking on BBC Radio 5 live, former England captain Shearer added: "He's a huge figure at the club. He loves the place and the passion of fans - and it's hugely important Newcastle keep hold of him.
"I'm sure he will demand the team has to be improved and will demand a few quid to do that.
"You can't stand still. You can't be loyal and give all the players that have got the team promoted a chance. You've got to go out and buy new players.
"People realise the team needs improving to get to where they want to be and that's got to be the top half of the Premier League.
"Now it's about where Newcastle want to be - do they want to get up to the Premier League and be in the bottom three or four fighting against relegation, or do they want to have a go at it? I'm pretty sure I know what Rafa will want to do."
Former Newcastle winger Chris Waddle echoed Shearer's view and believes Benitez will be in demand.
"The fans love Rafa - obviously - but I think Rafa will have a lot of tasty offers on the table from around Europe," Waddled told BBC Radio 5 live.
"If he doesn't get the reassurances he needs to strengthen his team - and I mean strengthen it - he's probably going to be looking elsewhere.
"I know fans will not want to hear that but he'll not want to be in a relegation battle next year."
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Now is the time to buy and build - Stone
Benitez was appointed by Newcastle in March 2016 but could not save them from relegation to the Championship.
He had a break clause in his contract allowing him to leave if the Magpies went down, but instead the former Liverpool and Chelsea boss opted to sign a new three-year deal.
One of the most expensive squads in Championship history was assembled last summer, mainly using funds generated from the sales of Moussa Sissoko, Georginio Wijnaldum, Andros Townsend and other high-profile departures.
Monday's victory over North End secured an immediate return to the top flight with two games to spare and ex-Newcastle keeper Steve Harper hopes the Magpies hierarchy give Benitez £60m to strengthen.
"He generated a £30m profit last year and you'd like to think they might give him double that," Harper told BBC Radio 5 live.
"Matt Ritchie and Jonjo Shelvey have had excellent seasons but I think every single Newcastle fan would want to see another five or six definite starting line-up Premier League players arrive so, when they go back, they're set up to compete.
Nobody will know that better than Rafa Benitez. He's united the fans again with his honesty and his integrity.
"He knows his stock is high. He's in a very strong position so he can ask the serious questions now and, hopefully, they do back him."
Against Preston, Christian Atsu put the Magpies 2-1 up at half-time after Jordan Hugill had cancelled out an Ayoze Perez opener.
On a tense evening at St James' Park, Newcastle nerves were settled when Preston's Paul Gallagher was sent off for handling on the line and Ritchie scored the resulting penalty.
Perez got his second from close range to send Newcastle up with Brighton.
Former Newcastle coach Steve Stone also believes the squad needs strengthening again at the end of the season.
"They still need an awful lot of new players before next season," he told BBC Radio 5 live.
"Fans realise they're not going to win the Premier League next season and they will struggle to get into the top 10. They need to get a foothold in the Premier League first, otherwise they will become a yo-yo club.
"It's been a long time since Newcastle were battling at the top of the Premier League. They finished fifth under Alan Pardew the season I was there (2011-12), but they haven't been up there on a consistent basis since Bobby Robson left (in 2004).
"Now is the time to buy and build, and make sure club doesn't have to play in this division ever again."
Former Nottingham Forest and England midfielder Stone added: "The fans absolutely adore Rafa Benitez and they have from the start. They chanted his name throughout the game.
"But he knows now that he needs money and it will be interesting to see if they give him the money he deserves.
"Everywhere Rafa goes, he gets a massive reception. Newcastle were lucky to get him - they needed him more than he needed Newcastle.
"Since getting here he has realised what it's all about and he's bought into it."