Chelsea travel to Barcelona looking to cause an unlikely upset and knock out the 2015 winners in their own backyard.
The Blues have previous, with their last visit to the Nou Camp coming in the 2012 semi, where they saw out a 2-2 draw to go through to the final on aggregate, where they would later lift the trophy.
Here's who Antonio Conte could pick for the trip to Catalonia:
Thibaut Courtois will start as usual.
With no pressing injury problems, Antonio Conte can name his strongest defence for the visit of Ernesto Valverde's men.
Youth prospect Andreas Christensen - now a regular starter after a break through season - will face the biggest test of his young career on Wednesday. The Dane made the vital mistake which led to Barcelona's away goal in the first leg and will be looking to make amends.
Cesar Azpilicueta and Antonio Rudiger will start alongside him. The three will have the unenviable task of containing the attacking brilliance of Lionel Messi and Luis Suarez.
Tiemoue Bakayoko is injured, and will play no part in Tuesday's game.
N'Golo Kante will be tasked with marshalling Andres Iniesta and the exceptional Barca midfield, with Cesc Fabregas looking to provide assists at the other end of the pitch, playing against his former club for the first time since his departure.
Victor Moses and Marcos Alonso will return in their usual wing-back roles; both having been rested on Friday night.
Despite Olivier Giroud's good start at Stamford Bridge, grabbing a debut goal against Hull, Eden Hazard has been turned to up top in the big games and should continue here.
Pedro could play against his former club in his return to the Nou Camp after his move in 2016.
After two goals and a man-of-the-match performance in the FA Cup, Willian is set start on the right wing. Eden Hazard is Chelsea's main hope of getting through this tie, and will be called upon to deliver a good performance.