Unbeaten in the league after 13 days, the Parisians, deprived of three players tested positive for Covid-19, recorded their first setback of the season on the national scene in front of the Chambers 29 to 28.
In the other semi-final, Nantes overthrew Montpellier 27-26 to win their fourth final in this competition and will aim for a second success after 2015.
The Savoyards seemed to be heading for an easy victory, leading by seven goals with twenty minutes to go (21-14), thanks to a flourishing collective in which six players scored more than three goals (including five from Alexandre Tritta and by Alejandro Costoya).
But they had to postpone a return from PSG (24-24), aided by the invigorating entry of young center-back Sadou N'Tanzi (4 goals).
A loss of ball from Nikola Karabatic 30 seconds from the end put an end to the hopes of a quadruple of the Parisians, who were deprived of goalkeeper Yann Genty, Benoît Kounkoud and Adama Keita.
Chambéry, titled during the first edition of the Coupe de la Ligue in 2002, will try to win a second coronation, ten years after failing in the final in front of Montpellier (32-29).
Nantes, 2nd in the French championship, relied on the performance of Danish goalkeeper Emil Nielsen (17 saves at 42.5%), author of a decisive save 40 seconds from time, before the Macedonian veteran Kiril Lazarov ( 41 years old) does not release his family twenty seconds later.
Nantes players greet their supporters, during the match against Paris Saint-Germain, for 3rd place in the Final Four of the Handball Champions League, June 13, 2021 in Cologne Ina Fassbender AFP / Archives
Another former, Spaniard Valero Rivera, 36, finished top scorer with 8 goals (72.8%).
© 2021 AFP