Redknapp says Blues fans must be realistic about top four.
Jamie Redknapp believes the Blues must give Frank Lampard time to succeed as Chelsea boss.
The former Blues legend was appointed as Maurizio Sarri’s successor on Friday following the Italian’s departure in June to Serie A club Juventus.
The announcement came after Lampard led Derby County to the Championship play-off final, where they lost to Aston Villa, in his first season as a manager.
However, former Tottenham and Liverpool star says Chelsea must "be realistic" about their top-four hopes in the 2019-20 campaign.
He told SkySports.com: "It's a great move, not just for Frank but for Chelsea too. It's astute, you need someone who can stabilise the club somewhat when you've lost your best player and under a transfer embargo.
"They've got one of their own, the fans adore him. He'll need time, there'll be a lot of changes; you can't bring any personnel in to replace a big-name star like Eden Hazard. He'll need to be given time, but he will - because he's Frank Lampard.
"The expectation will be to finish in the top four, but they've got to be realistic. I think there'll be moments in the season where it'll be a struggle, because of the Hazard effect.
"It doesn't matter what manager you have - Guardiola, Mourinho, anyone - they are going to struggle without that quality of player. But if they were to finish in the top four, that would be an amazing season considering the embargo and everything else."
Lampard won the Champions League, four FA Cups and three Premier League titles with Chelsea.