By SABC Sport
16th December 2023
The home side had not led at any point in the contest until the clock was in the red, with Libbok adding the extras to a late try from replacement Andre-Hugo Venter.
Defeat means the defending champions have lost both of their opening matches in this year's Investec Champions Cup, and the threat of an early elimination hangs over the TOP14 side.
Under the South African sun, it was La Rochelle who looked most at home during the first-half.
Both the French side and Stormers scored two penalties apiece via their flyhalves, Antoine Hastoy and Libbok respectively, but they were separated at the break by the only try of the first period.
That came via La Rochelle scrumhalf Tawera Kerr-Barlow, who had an easy finish after a remarkable run down the right wing by hooker Pierre Bougarrit, with Hastoy converting to leave the defending champions 13-6 up at the break.
Libbok's third penalty was the first score of the second period, but No 8 Yoan Tanga went over for the French side’s second converted try moments later.
But La Rochelle failed to get clear of their hosts, with Stormers striking back via Ben Loader in the 51st minute, the wing collecting a cross-field kick from centre Damien Willemse to score the United Rugby Championship side's first try.
Libbok failed to convert, but the South Africans were now on the front foot and the two-time champions found themselves having to dig in and defend for the remaining half an hour of the game.
It looked as if Hastoy had given the TOP14 side the win with a late try of his own, but it was called - back even after he converted - for head contact in the build-up which saw Joel Sclavi sent to the sin-bin.
That set the stage for a remarkable closing few minutes, with Venter's try and Libbok’s conversion condemning the defending champions to their second loss in a row.
La Rochelle now find themselves needing a big performance in their next match against Leicester Tigers at home in January, while the Stormers will face Sale Sharks at the DHL Stadium.