5) Romelu Lukaku – Inter to Chelsea – £97.5m (2021)
Re-signing their former player from Inter Milan looked to be a sensible decision by the Blues at the time.
Thomas Tuchel’s side had had their issues scoring goals and the addition of a new striker, who had hit the back of the net 30 times the previous campaign, seemed a good bit of business.
However, it quickly became clear that Lukaku wasn’t the right fit for Chelsea and, within months, the Belgian had spoken out to say that he wished that he had never left Inter.
After just one season, and eight league goals, he returned to the Serie A club on loan. The Blues are unlikely to recoup even a third of his transfer fee if the forward leaves Stamford Bridge on a permanent basis this summer.
