The defending Premier League champions are in negotiations with Courtois and Hazard about extending their deals to dissuade Real Madrid from pursuing their apparent interest.
Hazard has established himself as Chelsea’s key player over the past three and a half seasons following his influential performances in their title-winning campaigns in 2015 and 2017.
The Belgian forward scored 30 times in the 2014-15 and 2016-17 seasons to help Chelsea win the Premier League title at a canter under Jose Mourinho and then Antonio Conte.
Courtois has been ever-present in the Chelsea goal since his return from a three-season long loan at La Liga outfit Atletico Madrid.
The shot stopper is ranked as one of the Premier League’s top goalkeepers alongside Manchester United’s number one David De Gea.
Former Chelsea midfielder Lampard believes the Blues need to underline their intentions in the transfer market to persuade Courtois and Hazard to remain at Stamford Bridge.
“Chelsea have to show the ambition – if they want both of them to stay there, they have to keep adding to the squad in the right way,” Lampard told the Evening Standard.
“Great players such as Hazard and Courtois will always be looked at by Real Madrid, so to protect yourself you need to get them on long contracts.
“With the kind of money being spent elsewhere, Chelsea have to keep moving forward and recruiting new talent to play around them.
“The club can’t lose what they’ve got. Hazard is the main person there. He is 27 and a player of his ability has his prime years ahead of him. He will want to challenge for the Champions League but the club have to match that ambition as well.”
Chelsea finished in top spot and seven points clear of their closest challengers in the Premier League title race last term.
The Blues signed England international Ross Barkley in a £15m deal from Everton in the January transfer window.
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