Maurizio Sarri's side sit just four points below the Champions League spaces, whilst against all odds, Neil Warnock will be aiming to climb out of the relegation zone. The fate of a season may rest on the final result.
Their previous encounter ended sweetly at Stamford Bridge, a goal from Willian accompanied an Eden Hazard hat-trick as Chelsea ran out 4-1 victors. A similar finish would ensure the European quest is back on; failure and the campaign plus Sarri's reign may come crashing down around him.
Before the battle at the Cardiff City Stadium, here is five key areas the Blues must concentrate if they're to bring down the Bluebirds.
Put the transfer ban to back of mind
This is easier said than done, especially as the prospect of losing your most valuable asset in Hazard seems a foregone conclusion. The ban in question is what FIFA brandished towards Chelsea, after breaching rules about signing minors.
It is just one of many dark clouds culminating over the club, but this must be put aside and focus on the task at hand. Therefore, the likes of Chelsea's number ten, N'Golo Kante and to an extent, Callum Hudson-Odoi, who may all depart in the summer have to avoid imagining the vast cheques they might receive, or the all year round sun they might be soaking up.
Chelsea's loan brigade is bolstered with strong, emerging talent, some likely to play in the Premier League again next season. This should be an incentive for the current crop to raise their game, as to maintain their place in the starting line up or on the fringes.
All though winning the Europa League looks the most likely avenue into European football again next term, a place in the top four is what Chelsea demand and expect, let alone ultimately save Sarri his job, hence the need to pick up the three points.
Build on Bamba's absence
Warnock has woven a dogged resilience into his team that has earned them eight clean sheets this term in the league, goal difference looking decisive in the relegation rat race.
Cardiff couldn't have achieved this without Sol Bamba, who has featured in seven of those eight shut outs, missing the most recent against West Ham through injury. Bamba is set to be on the sidelines until next season, meaning Sean Morrison and Bruno Ecuele Manga are likely to partner at centre-back.
Although the pair are well acquainted as part of a four, Morrison and Manga are relatively inexperienced at the heart of the defence and Chelsea must exploit this. In fact, it was Bamba who scored Cardiff's goal in the defeat at the Bridge back in September.
An abundance of stars abroad
Sarri showed his displeasure towards several of his stars being hampered by tiredness after they featured during the international break.
Agreed, the constant travelling across countries will take a toll to a degree, but these athletes have been trained to combat such occasions. Plus, the last two weeks have been rather royal for those Chelsea players representing their nations.
Olivier Giroud scored in both of France's European Championship qualifying wins, Hazard marked his 100th Belgian cap by getting on the score sheet, Antonio Rudiger started the remarkable 3-2 comeback against Holland and English duo Ross Barkley and Hudson-Odoi shone as England excited once again.
The Blues boss showed build on these positives and push his players to emulate those feelings onto the field. Gonzalo Higuain also announced his retirement from the international stage, so his concentration should be on increasing his tally of three goals in England thus far.
Homegrown talent take charge
As mentioned, the Three Lions let loose during their two qualifying games, knocking a combined ten past the Czech Republic and Montenegro.
Aside from Raheem Sterling's hat-trick against the Czechs, and silencing the Montenegrin fans, a set of Blues brought back the positive publicity. Barkley's introduction at Wembley changed the tie in England's favour, earning a start in the next fixture and rewarding Gareth Southgate with a brace and an assist.
Not to be outdone, Hudson-Odoi became the youngest debutant in a competitive international, swiftly followed by his second cap in the starting lineup. It was his shot that Barkley ultimately stabbed home for the second in Montenegro as the 18-year-old lavished in the limelight.
The equation is simple; start at least one of the two, or go one better and throw them both in from the first whistle. Barkley provides a gear that Mateo Kovacic has not been able to change into and you can imagine Hudson-Odoi has a point to prove to his manager.
Rewind and replay
Watching the likes of Manchester United and Arsenal beginning to surge up the table should be a concern for Chelsea, however, they must focus on the task laid out in front of them. The Blues still need to travel to Old Trafford in the league, meaning three points in Wales will be vital.
If it is possible, play without pressure. Take the last meeting for example; Sarri's side had a swagger about them as they found a way past Cardiff on four occasions earlier in the campaign. This was sandwiched in Chelsea's 12 game unbeaten run under their new manager, plus the last in a five-match winning streak. It was the kind of performance to look back on for inspiration.
Hazard had one of those afternoons where he is untouchable, Giroud gave his typical elegant display, all being tied up with a trademark Willian rocket. The sun was shining over Stamford Bridge that day, but can Chelsea pull out another downpour on their hosts?