
Luis Suarez scored twice for Sporting in the second half, sealing victory with a 90th-minute header after substitute Khvicha Kvaratskhelia had equalised for PSG.
Following victories for Real Madrid and Tottenham, PSG with 13 points, have dropped to fifth place provisionally before Wednesday’s matches – closely followed by Sporting.
Their home game against Newcastle in eight days will determine whether the Parisians avoid the two-legged playoff in February.
Despite being largely dominant, PSG were unable to convert their early advantage into goals.
Lisbon striker Suarez ignited the home crowd with a clinical finish to beat Lucas Chevalier after 74 minutes. A poorly cleared corner followed by an unfortunate deflection proved fatal to the hitherto impenetrable Parisian defence.
Kvaratskhelia levelled after 79 minutes but Suarez struck again late.