Chelsea's new owners are prepared to keep spending in January to improve the squad.
The Blues shelled out £273 million in the transfer window this summer.
However, they were focusing on replacing players who had left on free transfers or loans, such as Antonio Rudiger, Andreas Christensen, and Romelu Lukaku.
Their only major midfield signing is Juventus midfielder Denis Zakaria on loan on deadline day.
According to the Evening Standard, co-owner Todd Boehly is aware the central midfield area needs improvement.
They may go back in for Ajax star Ajax's Edson Alvarez, while Barcelona's Frenkie de Jong is a target as well.