Antonio Conte's men are clear underdogs despite a good recent record against Barcelona, with the visitors building an all-time great unbeaten run domestically, and sailing through the group stages with minimum effort.
The west Londoners have had an indifferent start to 2018, being knocked out of the Carabao Cup last month after a run of five successive draws. Heavy defeats to Bournemouth and Watford followed, with serious questions being asked about Antonio Conte's position.
The slide has stopped for now, with comfortable home wins over West Brom and Hull in the past week offering much-needed respite to the champions, who sit a distant fourth, well behind leaders Manchester City with the defense of their title all but over.
By contrast, Barcelona have had a record-setting season, unbeaten in La Liga after 24 games, with a healthy seven-point lead over closest challengers Atletico Madrid.
Having been knocked out at the quarter-final stage by Juventus last season, the Catalans will be hoping for an improved showing in Europe as they look to reach a first final since their 2015 victory, hoping to deny bitter rivals Real Madrid a historic third Champions League win in a row.
David Luiz and Tiemoue Bakayoko are dealing with injury problems and are unlikely to feature on Tuesday night. Ross Barkley is still working through the hamstring problem that kept him out of the first half of the season. and will not start against La Liga leaders.
Ernesto Valverde has no new injury concerns, with Thomas Vermaelen a doubt for the tie, but unlikely to feature in the starting XI regardless, boasting a fully fit squad otherwise.
Ousmane Dembele has been passed fit and could start against the English champions, while club-record signing Philippe Coutinho is cup-tied, having featured for Liverpool in the group stages.
Predicted Chelsea Lineup: Courtois; Azpilicueta, Christensen, Rudiger; Moses, Kante, Fabregas, Alonso; Willian; Hazard, Morata.
Predicted Barcelona Lineup: ter Stegen; Roberto, Pique, Umtiti, Alba; Paulinho, Rakitic, Busquets, Iniesta; Suarez, Messi.
With Chelsea having a rough season and Barcelona looking dominant on all fronts, all signs point to a victory for the away side. However, the Blues historically have an excellent record against the Catalans, unbeaten in their last seven meetings and having won three of their last five encounters at Stamford Bridge.
Lionel Messi has never scored against Chelsea, with his missed penalty in 2012 bound to play on his mind as he looks to break his duck against a rare bogey team.
Despite improved form in the past couple of matches, this will be a sizable test for the west Londoners and it will take some performance to stop the Barcelona juggernaut.
Prediction: Chelsea 1-1 Barcelona