Former Cardiff manager Malky Mackay signed striker Andreas Cornelius for £7.5m in July 2013
Cardiff City owner Vincent Tan has called former manager Malky Mackay an "idiot" for his signing of Andreas Cornelius in July 2013.
The Danish striker, then 20, arrived for a club record fee of an initial £7.5m but failed to score in 11 games.
He rejoined FC Copenhagen six months later and the episode was one of the reasons for Mackay's sacking in 2013.
"It was unfortunate that we only stayed in the Premier League for one season," said Tan.
"You know the main reason, I always say, and I have told Mehmet [Dalman, Cardiff's chairman] the same, is that we spent a lot of money there - I think it was £50m.
"What did we get? We paid £10.5m for Cornelius who didn't even play 45 minutes and then the manager said he was a project.
"I'm in the Premier League, I need to survive. What an idiot he [Mackay] is."
Mackay's representatives told BBC Wales Sport they had nothing to say regarding Tan's comments.
Copenhagen paid in the region of £3m for Cornelius, who agreed to drop back down to his original salary of £6,000 per week, having been on £45,000 at Cardiff.
The striker was Scotsman Mackay's first signing after guiding Cardiff to promotion to the Premier League, and the Dane rediscovered his form at Copenhagen with a tally of 45 goals over his two spells with the club.
Cornelius joined Italian Serie A side Atalanta this summer for a fee thought to be close to £4m.
It transpires that, with add-ons, Cardiff's actual transfer fee for the striker was almost £11m and Cornelius's salary over a five-year contract, plus a £1.25m signing-on fee, meant the Bluebirds committed themselves to a total outlay of more than £20m.
Cardiff broke their record transfer fee twice more under Mackay, with Steven Caulker joining from Tottenham for £8m before Gary Medel was recruited from Sevilla for £11m, with both players proving a success on the pitch.
Following Cardiff's relegation after one season in the Premier League, defender Caulker was sold to Queens Park Rangers for £8m and Chile midfielder Medel to Inter Milan for £9m.
Cardiff owner Vincent Tan and ex-manager Malky Mackay celebrate winning promotion to the Premier League in 2013
Tan's acrimonious sacking of Mackay - who is now the Scottish Football Association's performance director - was one of several flashpoints in what has been a tumultuous tenure since the Malaysian businessman bought the Welsh club in 2010.
Cardiff subsequently sent a dossier to the Football Association alleging that Mackay and former head of recruitment Iain Moody shared racist and sexist texts, with the governing body deciding that both men would face no action.
Tan's decision to change the team's home colours to red led to a fans' revolt but his financial support for Mackay was central to the club's promotion to the Premier League in 2013, albeit for only one season.
The owner agreed to a return to blue shirts in 2015 and, although the club seems to be enjoying a period of stability under manager Neil Warnock, Tan remains furious with Mackay and his signing of Cornelius.
"Neil is sensible. He knew the problems we had and the mistakes we have made before. So Neil is doing a great job and we are happy with Neil," said Tan.
What rubbish is that?
"The fans should be together with us because we're trying to do the right thing," he added.
"We haven't got a manager who will do the wrong thing - Neil is doing the right thing.
"So if the manager does the right thing and we also do the right thing - we support when it is supportable.
"We cannot support someone who makes ridiculous decisions, stupid decisions.
"You pay for a big striker £10.5m you should play him 90 minutes, not 45 minutes, five minutes, 10 minutes. Because he's a project he [Mackay] says, finally, he says he [Cornelius] is a project.
"How come I'm in the Premier League and you're finding time to do a project for the future? What rubbish is that? And you pay £45,000 a week for a project? Rubbish!"
Cardiff have meandered in the Championship in recent seasons, gradually reducing spending as they enter their final year of parachute payments following their Premier League relegation.
Neil Warnock took over as Cardiff manager in October 2016
They have made a strong start to this campaign - their first full term under Warnock - and sit top of the Championship table after two wins from their opening two fixtures, including Saturday's 3-0 victory over Aston Villa.
Tan believes the club is more stable and harmonious than it has been for much of his controversial reign, and he thinks Warnock could help them mount a promotion challenge this season.
"I think we have a very good chance to get promoted, but I always say God willing," he said.
"We will try to be humble and we pray for good luck because luck is important.
"I think we are lucky, we got good luck, we have got Neil - thanks to Mehmet because we could have got someone terrible.
"But we have got Neil, we are happy and if we get promoted I think we have a good chance of staying if we do things sensibly - as long as we don't spend £10m on a striker!
"If you do that he must score 10 or 20 goals. We had one not even play 90 minutes and paid the highest salary in the club's history - £45,000 a week.
"I can't believe it even still today."