Middlesbrough are facing the prospect of a massive summer in the transfer market.
Neil Warnock has made no secret of his desire to make huge changes to the playing squad as he looks to move a handful of players on and replace them with individuals who are capable of guiding the club to promotion.
Doing that, however, could be tricky.
Part of the summer rebuild could come down to sell on first team players.
The club have worked hard in recent years to sign young, talented players who could potentially be sold on for a profit in the future.
But which players have seen their value increase the most since first appearing for the club?
Here are the top 10 Middlesbrough players who have had the biggest market value increases since their debuts, according to Transfermarkt.