Sunderland manager Lee Johnson has already started his preparations for the upcoming transfer window by launching a complete overhaul of his squad.

As well deciding to part ways with a host of players who ultimately failed to deliver the goods during the previous campaign, the Black Cats boss has also decided to offer new contracts to some of the club's stand-out performers.

Whilst talks between Sunderland and Charlie Wyke are ongoing, new deals have been tabled for Aiden McGeady and Luke O'Nien.

However, with O'Nien attracting a great deal of interest from elsewhere, there is no guarantee that the Black Cats will be able to keep him at the Stadium of Light this summer.

A recent report by Football Insider revealed that Preston North End, Millwall, Middlesbrough and Luton Town are all monitoring the defender's situation ahead of potential swoops.

If O'Nien decides to call time on his stint at Sunderland, he will be available on a free transfer as his current deal is set to expire later this month.

Making reference to the 26-year-old's situation, former Black Cats forward Kevin Phillips has admitted that he believes the defender will commit his future to the club despite the fact that he is being linked with a move to the Championship.

Speaking to Football Insider, Phillips said: "I think he will stay to be honest, I think he loves Sunderland.

"He seems like a real loyal guy.

"As I know well, they're very hard to find and if someone is coming in with a better offer and the chance of playing in the Championship then it's hard to turn down, but it's clear that he does like the club.

"If they want to keep O'Nien they're going to have to offer him a decent contract, but not to the point where they're being held to ransom, so it's getting that balancing act right.

"But I think if you offer him a good, decent contract, then he would stay."

GIVEMESPORT's Joshua Cole says...

If Sunderland are to put the disappointment of suffering defeat in the play-offs behind them next year by sealing promotion to the Championship, it is imperative that they keep O'Nien at the club this summer.

As well illustrating a great of versatility last season by featuring in a host of different positions, the defender also averaged a WhoScored match rating of 6.95 in League One which was only bettered by two of his Sunderland team-mates.

An accomplished player at this particular level, O'Nien knows exactly what it takes to compete in the third-tier having played 110 games in this division during his career.

Therefore, if Sunderland were to lose him in the coming weeks, it would be a major blow as there is no guarantee that they will be able to draft in a sufficient replacement.

Read More - Everything you need to know about the summer transfer window!