PSG knew that a win and other results going their way on Saturday would seem them crowned champions and they flew out of the blocks.
However, the hosts soon gained a foothold in the game and went ahead with 17 minutes gone, as Cabella tapped home from close range after PSG failed to deal with Mathieu Debuchy's cross from the right.
That gave the hosts a huge boost and they soon went close again as Romain Hamouma saw a powerful effort well saved by Alphonse Areloa in the visiting goal after meeting Debuchy's cutback.
Just 12 minutes after their opener the hosts were handed a glorious chance to double their lead as they were awarded a penalty when Presnel Kimpembe was adjudged to have brought Hamouma down unfairly.
Cabella took responsibility from the spot but Areola kept out his tame effort away to his right.
6 April 2018
Despite that blow, the hosts continued to look the better side and were given a huge boost four minutes before the break as Kimpembe was given his marching orders for a second bookable offence.
- Second-half fightback -
Their one-man deficit didn't seem to faze PSG too much though they were on the back foot once again in the early stages of the second half.
Kylian Mbappe saw an effort briliantly blocked away by Gabriel Silva on a rare foray forward for the visitors, before Jonathan Bamba really ought to have made it 2-0 to Saint-Etienne when he hooked over from range after Neven Subotic flicked on a corner.
Substitute Ousama Tannane rattled the crossbar on the counter-attack with just over a quarter of an hour to go, before Saint-Etienee were let off the hook as Edinson Cavani inexplicably fluffed his lines from 12 yards with the goal gaping.
Angel Di Maria was set away through the middle and he raced clear before squaring for the Uruguayan byut he somehow rolled an effort wide of the post with Stephane Ruffier beaten.
PSG went close again in added-on time at Cavani's directed a cross from the left goalwards but Ruffier was alert enough to make a sharp stop.
There was nothing he could do just a minute later though as a cross was sent in from the right, Mbappe rose to flick it on and it took the hapless Debuchy by surprise at the far post to bounce off him and into the back of the net to earn PSG a point.
The resulkt leaves the Parisians 17 points clear of Monaco in second, with next week's clash between the pair now a potential title-decider. Saint-Etienne remain 9th.
6 April 2018