A perplexing encounter was goalless until the 77th minute when Denis Bouanga had Saint-Etienne in front and PSG, beaten in their previous three home Ligue 1 games, facing defeat again.
Kylian Mbappe leveled just 84 seconds later, though, and then won and converted a penalty to seemingly win the match and close to within a point of leaders Lille, held by Montpellier on Friday.
86 - Kylian Mbappé has scored 86 goals with Paris in Ligue 1, becoming the only 3rd all-time goal scorer of the team in the top-flight (Mustapha Dahleb with 85). The French forward is now only preceded by Zlatan Ibrahimovic (113) and Edinson Cavani (138). Podium. #PSGASSE pic.twitter.com/ShOS6MLIOr— OptaJean (@OptaJean) April 18, 2021
Yet that was far from the end of the drama, with an awful error from stand-in goalkeeper Sergio Rico gifting Romain Hamouma a 92nd-minute equalizer.
Saint-Etienne had just three more minutes to see out to protect a point but allowed Icardi, back after a month out with a thigh strain, to reach Angel Di Maria's cross and nod in to spark jubilant celebrations.