Sunderland are understandably desperate to finally seal a promotion back to the Championship this season.

Boss Lee Johnson might have some work on his hands to strengthen his side in January to try and ensure they can compete in the top six for the remainder of the campaign.

The Black Cats have had their ups and downs already this year, with the side looking unbeatable and genuine promotion contenders one week before stumbling a week later and looking shaky.

They have some solid players currently at their disposal and some prolific goalscorers too - but they'll need to ensure they can consolidate their position for the rest of the season and that might mean some January spending.

But who could leave to make way for some incomings in the winter transfer window?

Aiden O'Brien

Aiden O'Brien has proven to be a decent squad option for Sunderland so far this year and has managed 12 appearances, which isn't bad whatsoever. It's not like the player isn't getting regular action at the Stadium of Light.

However, he's had a lot less starts than he did last year and there are a number of players above him in the pecking order at the club. If even more come in during the winter window, it's likely to see even more of a drop off when it comes to his time on the pitch.

Another issue is that his current deal with the club runs out at the end of the season. If he isn't a first-team regular and isn't deemed as essential by Lee Johnson, then he could end up seeing his contract out and just leaving for nothing at the end of the year.

There is a decision then for Sunderland to make over the player. Should they find someone as a replacement for O'Brien already and let him leave for a small fee in January rather than risk losing him for nothing in summer or do they hold onto him for use in the squad for the remainder of the season?

There would no doubt be interest in his services if he became available due to his experience and the fact he can score goals at third tier level - so if there is suitable interest and a suitable bid, then he could certainly be allowed to leave before his contract expires.

Ollie Younger

Ollie Younger appears to be a decent young talent for the Black Cats. However, right now he is struggling for much action at the Stadium of Light.

He's 22-years-old now but has only managed one game for his current side so far. With the player now getting to the point where he needs regular action and experience, it could be worth touting his services in January and seeing if anybody would want to take him on a short-term deal.

Younger is unlikely to play much for the club this campaign - he hasn't got a single minute so far and has instead been confined to the reserve side - so it would be worth him trying to play first-team football elsewhere.

He's only on a one-year deal with Sunderland and he needs to prove he is a talent worth keeping at the club - and if he can't get on the pitch and do it with the Black Cats, then he should certainly explore leaving in January and doing it elsewhere.