LONDON -- Guus Hiddink has warned the Chelsea hierarchy that the squad needs greater depth if the Blues are to compete for the Premier League title while fighting for multiple trophies next season.
Last month, former boss Jose Mourinho claimed that a lack of significant investment in his title-winning Chelsea squad during the summer sowed the seeds for the disastrous run of results and "palpable discord" that brought about his sacking in December.
Hiddink has overseen a dramatic revival since returning to Stamford Bridge for a second interim spell, losing one of 15 matches in all competitions to lead Chelsea up to 10th in the Premier League and into the quarterfinals of the FA Cup.
But the Dutchman warns that the Blues' recent progress will prove unsustainable if owner Roman Abramovich does not invest to give the next Chelsea manager -- widely expected to be Italy coach Antonio Conte -- a wider range of squad options next season.
Asked if he expected to see Chelsea back at their expected level next year, Hiddink replied: "That's up to the new management, of course. My personal opinion is that when you play in the Premier League, the FA Cup, the Capital One Cup and the Europa League, you need a broader squad.
"I'm a little bit, scared is not a good word, but that must not happen a lot with our players. We have 13 or 14 outfield players and we cannot afford a lot of damage [in terms of injuries]. When you play in five competitions you need to broaden your selection."
Chelsea's run of three consecutive Premier League victories leaves them 10th in the table, just eight points adrift of fifth-placed Manchester United with 10 matches to play. Hiddink insists that should they qualify, Europa League football would be a positive for the Blues next season, despite fears of fixture congestion.
"If you play in the Europa League you can also bring young players in," the Chelsea boss added. "I don't want to undervalue it but it is a nice league, a nice competition to have games for younger players. We try to have younger players and it is a nice podium for them to act."