Chelsea take on Atletico Madrid on Wednesday night as they bid for a place in the Champions League final.
Here we look at the key battles which could determine the semi-final second leg at Stamford Bridge.
John Terry v Diego Costa
Captain Terry is expected to win his fitness battle following an ankle injury, which will be tested by prolific scorer Costa, who is reportedly coveted by Chelsea.
Terry will receive able support from Gary Cahill and Branislav Ivanovic, who missed the first leg through suspension.
Cesar Azpilicueta v Raul Garcia
The anticipated return of Terry reunites Jose Mourinho's first-choice back four, with Azpilicueta back at left-back in place of England centurion Ashley Cole.
Goalscoring midfielder Raul Garcia will test Azpilicueta, particularly in the air, and challenge his compatriot's status as Chelsea's number one left-back.
Eden Hazard v Juanfran
Belgium playmaker Hazard, the PFA Young Player of the Year, has not been seen on the pitch since limping forlornly off during the second leg of the last round against Paris St Germain, Chelsea's prospects seemingly disappearing with their most startling performer this season.
Hazard, who has declared himself fit following his calf problem, has a chance to show his magic and help the Blues to the final. The experienced Juanfran must try to stop him.