Los Rojiblancos seemed destined to fall into the Europa League after taking just three points from their first four Group C games but a 2-0 triumph over Roma last time out gave them an outside chance of reaching the knock-out stage.
Diego Simeone’s side are third in the standings on six points, with Roma two better off in second and Antonio Conte’s Blues top of the tree on 10 and safely through to the last-16.
It will be tough for the Spaniards to stay in Europe’s elite club competition as they must to win at Stamford Bridge and hope Roma slip up at Azerbaijan Premier League side Qarabag.
Both scenarios are possible, if highly unlikely, and it is this that will drive Luis and his team-mates on in west London.
"This will be a very difficult game for us, but we must not stop believing," he told reporters. "It is important not to give up hope and to keep going, even though we know we will need to rely on a team other than just ourselves.
"In terms of the rest of the season, we must be more proactive in games and take the initiative as we are leaving ourselves too vulnerable to drawing matches."