Chelsea will have to exclude one of their big-name signings this January from their Champions League squad.
The Blues will play Borussia Dortmund in the last 16 with the first leg in Germany on February 15 and the return leg at home on March 7.
The Blues owner, Todd Boehly completed a splurge this month with Enzo becoming their eighth signing breaking, the British record deal on deadline day.
Other arrivals include Joao Felix on loan from Atletico Madrid, Mykhailo Mudryk (£88m), and £35m for Benoit Badiashile.
However, UEFA rules stipulate that only three new players can be
registered for the knockout stages.
It means Chelsea must decide which three out of the eight new faces Graham Potter will add to their squad before Thursday night.