Former chairman Freddy Shepherd feels England striker Michael Owen must repay his debt to Newcastle.
Shepherd bought Owen for £17m from Real Madrid
Owen's knee problem was one of a number of injuries that stalled the Magpies' campaign last season and they could only finish 13th in the Premier League.
Shepherd, who left the club last week, told BBC Five Live: "Michael Owen owes Newcastle a lot. I think he's played more times for England than Newcastle."
Owen joined in 2005 and played 11 games before breaking a bone in his foot.
The England striker, 27, then ruptured his anterior cruciate knee ligament at the 2006 World Cup and only made his comeback for Newcastle in May.
Owen's future at Newcastle has been the subject of speculation since it was revealed he has a £9.5m buy-out clause in his contract.
But Shepherd - who sanctioned Owen's Newcastle contract - claims the clause expires on Tuesday.
Shepherd said: "Without the clause I don't think we could have done the deal, but it is only valid until 31 July.
"After that, he would have to stay for another year, unless it was in the club's interest to let him go."
Now Shepherd expects Sam Allardyce, who was appointed manager of Newcastle in May, to use the methods he employed as Bolton boss to bring Owen and the rest of the squad back to their peak fitness.
"I have every confidence Sam Allardyce will get the injury situation sorted out.
"From what I hear, the players have never been fitter," revealed Shepherd.
"Sam's got the mental strength and that was certainly needed at Newcastle. He brings a lot of discipline to the club and is nobody's fool.
"We tried to get Sam for two years and we have finally got him. I have every confidence he will do well."
I sold the club for £38m and I've done fantastically well for what was a hobby
Former Newcastle chairman Freddy Shepherd
Shepherd, who was replaced as chairman last week following Mike Ashley's takeover of the club, does not expect affairs off the pitch to affect preparations for the new season.
Police raided Newcastle as part of an investigation into alleged corruption earlier this month but Shepherd says the club are clear of any wrongdoing.
"The club have nothing to answer," said the 65-year-old. "We have done absolutely nothing wrong and are spotless.
"The police are looking for someone else and are trying to get evidence to stack a case up."
Shepherd relinquished control of Newcastle when he agreed to sell his 28% stake in the club to Ashley for £37.6m.
The former chairman was struck down by a bout of pneumonia and a collapsed lung when the deal was being finalised.
Allardyce joined Newcastle from Bolton in May on a three-year deal
But Shepherd, who became chairman in 1997, says he has no regrets about how his reign at St James' Park ended.
"My position as PLC chairman no longer existed and so there's no problem at all," he insisted.
"You need to be more than a multi-millionaire to own a football club these days. It's a new era at the club and I'm sure Mike will take it forward.
"I've still got my box and will go to the matches. I've been there since I was a kid and I'm certainly not going to stop now.
"I sold the club for £38m and I've done fantastically well for what was a hobby. Now I'm going back to my main businesses."