Chelsea must tie Eden Hazard down to a new long-term contract after being hit with a transfer ban, according to Jimmy Floyd Hasselbaink.
The Blues have been banned from signing any new players during the next two transfer windows, after FIFA determined they had breached rules regarding the registration of minors.
As revealed by Goal, the Belgian is keen to make the move to Madrid in the summer, although the Blues' transfer ban, which they've announced they do plan to appeal, could now muddy the waters.
Hasselbaink, who played at Stamford Bridge between 2000 and 2004, believes his old club must now make extending Hazard's current deal their number one priority.
"They can't replace him or get somebody who they can work on to become as good as Hazard," Hasselbaink told Sky Sports. "I know they have bought [Christian] Pulisic, but they will need more to replace Hazard.
"It's now about believing in Chelsea and them persuading him to sign a long contract."
Chelsea have endured a miserable 2018-19 campaign so far under Italian boss Maurizio Sarri, slipping to sixth in the Premier League and suffering a fifth-round FA Cup exit at the hands of Manchester United.
Sarri, who, as revealed by Goal, has three games to save his job, has been widely criticised for his rigid tactics and stubborn selection policy, which has seen the likes of Ruben Loftus-Cheek and Callum Hudson-Odoi restricted to only a few appearances across all competitions.
And Hasselbaink believes that Chelsea's transfer ban might benefit the younger players in the squad, with more opportunities likely to be forthcoming over the coming months.
"It's not good for Chelsea, particularly with how things are going at the present time," he added. "But on the other hand, you can spin it, in a way it is good news for the younger players like Callum Hudson Odoi and also Loftus Cheek, who now will get chances.
"They will have to look at their youth if this [transfer] ban is held."
The Blues are now gearing up to play against Manchester City in the Carabao Cup final this weekend, just two weeks after suffering an embarrassing 6-0 defeat against the Premier League champions.