The 2021 summer transfer window looks set to be a crucial one for those associated with Sheffield United.

Having finished bottom of the Premier League table last season following a dismal campaign, the Blades may need to rebuild their squad ahead of their new campaign, in order to compete for promotion back to the top-flight of English football in 2021/22.

Of course, that is something that may see Sheffield United spend a fair amount of money, and recently appointed manager Slavisa Jokanovic may already have some targets in mind as he aims for more promotion success in the Championship.

However, it is also worth noting that there are a number of players out of contract at their respective clubs this summer, who could both be useful additions at Bramall Lane, and save Sheffield United some useful funds in the process.

So with that in mind, we've taken a look at nine free agents and players who are out of contract this summer, who it may be worth the Blades considering a move for in the transfer market.

We start this list with a player who only narrowly missed out on promotion to the Premier League via the play-offs this season, in the shape of Swansea striker Andre Ayew.

Goals, or rather a lack of, was a major problem for Sheffield United last season, which they will want to address this summer, and having scored 17 league goals this season, backing up his 16 from the previous campaign, Ayew is someone who could help do that for the Blades.

He is out of contract at The Liberty Stadium this summer, and as given he is reportedly the highest-paid player in the Championship, Swansea may struggle to afford a new deal for the Ghanaian, although Sheffield United's financial windfall from their time in the Premier League means you wonder whether they could afford to swoop for the 31-year-old.

Another attacking option who could be worth considering for Sheffield United as they look to boost their goal threat, is Famara Diedhiou.

The centre forward is a free agent following his departure from Bristol City at the end of his contract last summer, having scored 51 goals in 169 appearances during a four-year spell with the Robins, showing he too knows the route to goal in the Championship.

At 28-years-old, Diedhiou also has plenty of time remaining in his career to make an impact, and amid suggestions the centre forward has priced himself out of a move to Middlesbrough, Sheffield United's Premier League finance boost could work in their favour here as well.

Another striker whose future look set to be the subject of much speculation over the course of the summer, in the wake of this season, is Charlie Wyke.

The centre forward enjoyed an outstanding 2020/21 campaign in front of goal for Sunderland, netting a total of 31 goals in all competitions, meaning he too could be an attractive target for Sheffield United were they to consider bringing him to Bramall Lane.

With Wyke's current contract at The Stadium of Light expiring this summer, the Black Cats have offered him a new contract, but having missed out on promotion to the Championship via the League One play-offs, it could be hard for them to keep hold of the 28-year-old, meaning there could be an opportunity here for Sheffield United, should they wish to take it.

With Phil Jagielka having been released and talks ongoing as Sheffield United attempt to secure the services of Kean Bryan, centre back is another position they may need to strengthen this summer.

One option for the Blades to look into in that position, is Tom McIntyre, who is currently in talks with Reading, with his current contract expiring at the end of this season, meaning there could be a chance for another club to move in here.

McIntyre has already shown this season that he is more than capable of holding his own in the Championship with his performances in Reading's play-off pursuit this season, and at 22-years-old, there is still plenty of time for him to improve even further.

It's probably fair to say that things have never quite got going for Jimmy Dunne during his time at Burnley so far.

The 23-year-old former Manchester United academy man has made just seven senior appearances for the Clarets since joining in 2016, despite the fact that the centre back is a player who does seem to possess plenty of promise for the future.

With that in mind, the fact that Dunne's contract is set to expire this summer means this could be worth looking into for Sheffield United as they look to boost their defensive numbers, with the Republic of Ireland youth international no doubt keen to really start making a regular impression in senior football.

With John Lundstram and Jack Rodwell having been released, and speculation linking Sander Berge with a swift return to the Premier League, centre midfield is another position Sheffield United may need to add to this summer.

Barnsley's Alex Mowatt is one player who should that happen, would surely be worth looking into, with the 26-year-old producing some outstanding performances this season to drive the Tykes on their unlikely run to a Championship play-off place.

That ought to suggest Mowatt could have a similar impact with Sheffield United, and while Barnsley are in talks with the former Leeds man about a new deal with his contract now coming to an end, the Blades' extra Premier League finances could help them to swoop in here should they wish to do so.

Another midfielder who could surely be worth looking into for Sheffield United this summer, is Mario Vrancic.

It has already been confirmed that the Bosnian midfielder will leave Norwich this summer, and given his experience as part of the Canaries' last two Championship title winning squads, he could certainly be useful for the Blades as they target promotion next season.

Indeed, Vrancic himself may well be keen to prove that he has still got what it takes to compete at the top end of the Championship even at 32-years-old, meaning this could at the very least be an intriguing proposition for those concerned.

Like Vrancic, another player who will surely want to prove that he can still compete at the higher levels of the football pyramid, and could therefore be worth considering, is Jack Wilshere.

The 29-year-old has now left Bournemouth after his short-term contract expired at the end of the season, and his vast top-flight experience could also be useful for Sheffield United as they target a Premier League return next season.

Indeed, for all the problems he has had with injury and opportunities in recent years, there is no doubting that Wilshere is still a high quality player, meaning he could yet be a big asset for the Blades if he can find some fitness in particular again, which at his age, he still has time to do.

One other position that Sheffield United might consider adding to this summer is in goal, where the departure of Simon Moore means the Blades may want to add another option alongside Aaron Ramsdale and Wes Foderingham.

Should that happen, then one option that could certainly be worth considering is Jordan Archer, who is a free agent after Middlesbrough elected not to hand him a new deal when his previous short-term contract at The Riverside expired at the end of the season.

The goalkeeper has plenty of useful Championship experience behind him from his time at Millwall, but has largely been second fiddle at the likes of Fulham, Motherwell and 'Boro since then, meaning he could fit a role such as this rather well at Bramall Lane.