Sunderland will be looking to all but secure a League One play-off spot on Tuesday evening in their clash with fellow promotion hopefuls Blackpool.

Having been on an excellent run of form since the appointment of Lee Johnson back in December, with the 39-year-old guiding the Black Cats to a run of 16 league games without suffering a single defeat between January and April, things have taken a turn for the worse in recent weeks at the Stadium of Light.

Over their last six League One fixtures, Johnson's side have now picked up a shocking totla of just three points, losing to Charlton Athletic, Wigan Athletic and Blackpool, as well as drawing with Peterborough United, Hull City and Accrington Stanley - with the club conceding a whopping 11 goals in this run.

The Black Cats' leaky defence has coincided with the loss of the Wolverhampton Wanderers loanee centre-back, Dion Sanderson, to a back injury, and the versatile central midfielder, Luke O'Nien, filling in at the centre of defence.

However, with the 26-year-old making a number of costly mistakes in recent weeks, as well as averaging a disappointing WhoScored match rating of just 6.3 over his last four appearances, it would be advisable for Johnson to move O'Nien out of the middle of his defence for Sunderland's must-win clash with Blackpool on Tuesday.

As for his replacement, Oliver Younger would appear to be the ideal candidate to step in, as, while the 21-year-old does not have much first-team experience under his belt, the defender was impressive on his debut against Fleetwood Town in the EFL Trophy, as well as convincing Johnson that he was ready for a league start against Rochdale back in March.

And, despite Younger's relative inexperience, his natural ability as a centre-back would likely benefit the structure of the Sunderland backline more than with O'Nien at its core.

Furthermore, considering O'Nien's performances in recent weeks, there does not seem to be a great amount to lose in replacing the midfielder with the young defender, but there is very much plenty to be gained.

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