Chelsea had known they would face one of Gent, Real Betis, Copenhagen or Heidenheim next, but now know that it is between just two of those sides after the conclusion of the play-off round.
FC Copenhagen's 4-3 aggregate win over Heidenheim and Real Betis' two-legged victory over Gent, means it'll be one of Betis or Copenhagen who face the tough task of taking on the Londoners.
As a seeded team, Chelsea will contest the away leg of their round of 16 tie on March 6, with the reverse fixture at Stamford Bridge scheduled for March 13.
A tie with Betis would mean Chelsea would have to deal with in-form Antony, who sealed a loan to the La Liga club in January and has been scoring for fun since.
Enzo Maresca's side bypassed the need for a play-off round and booked a spot straight into the last 16 proper thanks to their league phase efforts.
