Schwarzer told the Daily Star Sunday: "It's a big shame for us losing Frank, who has been an unbelievable player in the Premier League.
"He's a world-class player and it's a huge loss for Chelsea considering how long he has been at the club. But he's obviously looking for another challenge.
"With Cesc, you're talking about another world-class player replacing Lampard.
"That's what happens at the top end of the league and at clubs like Chelsea. Players of equal quality replace the old ones."
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