Atletico Madrid and Chelsea have agreed to a $44 million transfer for Conor Gallagher with Samu Omorodion returning to Stamford Bridge in a separate deal for $36 million.
Atletico had already agreed terms with Chelsea last week for the arrival of Gallagher but were waiting for the midfielder to accept the move.
Omorodion, 20, impressed while playing last season on loan at Deportivo Alaves from Atlético.