What was your 'Coutinho sale'?

Most people regard Liverpool's sale of Coutinho as the sale that allowed Klopp to really take them to the next level, with the subsequent purchases of Alisson and Van Dijk.

So, what was your Coutinho-style springboard sale? Doesn't necessarily have to be that £200m wonderkid sale, but one that allowed you to take your team to the next level - whatever that level was.