Maurizio Sarri's men were pressed against the ropes on Sunday when the relegation-threatened hosts took the lead in the first half through Victor Camarasa.
But with "Sarri out" chants circulating through the visiting end - answered by "Sarri in" from Cardiff fans - the Blues received a reprieve.
Cesar Azpilicueta was on hand to head the equaliser home just six minutes from time as he steered past Neil Etheridge.
The only problem, for Cardiff and neutral fans at least, was that the Spain international looked to be in a clearly offside position when he struck.
The full-back was one of two Chelsea men beyond the last defender when Marcos Alonso returned the ball into the danger zone, but the linesman's flag stayed resolutely down and Craig Pawson sanctioned the leveller.
To add insult to injury Ruben Loftus-Cheek swooped in injury time to hand Chelsea all three points, sinking Cardiff further into relegation woe and provoking a backlash across social media.
Anyone still questioning if we need VAR or not just needs to watch the highlights of the Chelsea game. Shocking.— Neil Bernstein (@nbernste) 31 de marzo de 2019
Can’t stand Chelsea or Warnock but these referees are getting worse, not better.— Graeme Kelly (@GraemeKelly1) 31 de marzo de 2019
I didn’t want VAR but there is no choice as the standard of officiating is rock bottom. VAR will be shite though. Won’t celebrate a goal properly again.
Cardiff 1 - Chelsea 1 - Lack of VAR 1— Poorly Drawn Arsenal (@cantdrawarsenal) 31 de marzo de 2019
Maurizio Sarri survives another day at Chelsea... 🚬 pic.twitter.com/P106Pvrv4l— FootballJOE (@FootballJOE) 31 de marzo de 2019
On behalf of Chelsea, I'm sorry @CardiffCityFC— Kristian Sturt (@FootieWriter) 31 de marzo de 2019
Big three points for Chelsea, but we can't rewrite history on it. It was a dire performance until Azpilicueta headed home from an offside position. Chelsea need to take the gift and improve now, points are all that matters, but they won't get many playing like that. #CFC #CARCHE— Nizaar Kinsella (@NizaarKinsella) 31 de marzo de 2019
Full time Cardiff 1-2 Chelsea— Footy Accumulators (@FootyAccums) 31 de marzo de 2019
Fair play to the Chelsea man of the match Craig Pawson... had a stormer ⛈ pic.twitter.com/wXtEqiE6CS
Chelsea are the attacking team in this situation... pic.twitter.com/WTQB8VPeOe— Back Page Football (@bpfootball) 31 de marzo de 2019