New manager Frank Lampard, who signed Tomori on loan at Derby in 2018/19, believes the centre-back is ready to compete for regular starts at Stamford Bridge this term.
And Chelsea will move quickly to secure their academy product's future by offering him fresh terms.
Tomori's current deal expires in summer 2021 but he should follow in the footsteps of Ruben Loftus-Cheek and Mason Mount in signing an extension.
Chelsea begin their Premier League season against Manchester United on Sunday.
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