Compensation could prove a stumbling block should Sunderland turn to Derek McInnes to replace David Moyes - but the Aberdeen boss remains the firm favourite for the Black Cats post.
The Echo understands that it could cost Ellis Short upwards of £1million to land McInnes, who has two years left on a supposed £300-400,000 per-year, plus bonuses, deal at Pittodrie.
But by no means is the deal dead, especially given that the 45-year-old has made it clear privately that he would jump at the chance to manage at the Stadium of Light.
Although, as yet, sources north of the border have confirmed that no official approach has been made for McInnes by Sunderland.
McInnes, who is on a pre-planned holiday to Florida with his family, was yesterday, for the first time in the best part of a week, knocked off the top of the boomakers list drawn up to replace fellow Scot Moyes, who resigned from his post over concerns about the club's budget.
A flurry of bets saw former Manchester United and Wales wideman Ryan Giggs installed as the odds on favourite.
But with Sunderland hunting for an experienced head to guide them in the Championship, Giggs appointment, at this stage at least, would seem unlikely.
McInnes lacks the experience in England's second tier, having nothing but an ill-fated spell at Bristol City on his CV, but has managed in Scotland's top flight with both the Dons and St Johnstone, with whom he won the Scottish Division One title.
Appointing the former Rangers and West Brom midfielder would not come cheap, though, following Aberdeen's moves to tie McInnes down to a long-term deal.
The Dons manager, along with trusted assistant Tony Docherty, signed a contract extension back in the summer of 2015, amid interest from Ibrox.
That deal runs until the summer of 2019.
And with budgets tight at SoL, following relegation from the Premier League this summer, the news that Sunderland may have to fork out a seven-figure sum would come as a concern.
McInnes is believed to be on a shortlist, drawn up by Martin Bain and former Ibrox colleague Walter Smith, along with out-of-work Garry Monk and Paul Lambert.
Barnsley boss Paul Heckingbottom has also been considered for the post, as well as Simon Grayson, of Preston.