The Sharks gave another demonstration of their inconsistent at Kings Park, where the Jaguares ran riot with a seven-try drubbing.
Matias Orlando scored a hat-trick as the Jaguares mauled the Sharks 51-17 and Handre Pollard inspired the Bulls to a comfortable Super Rugby victory over the Reds on Saturday.
The Sharks thrashed the Lions last time out, but they were brought back down to earth at Kings Park - where the rampant Jaguares scored seven tries to secure a fourth win of the season.
Tomas Cubelli, Pablo Matera and Orlando went over to give the Argentine side a 21-10 lead at the break, Hyron Andrews scoring the only Sharks try in the first half.
Gonzalo Quesada's men blew the Sharks away after the interval, Matera crossing again just two minutes into the second half and Matias Moroni adding another try following a Domingo Miotti penalty.
Aphelele Fassi took a fine offload from Curwin Bosch to score a second Sharks try, but Orlando claimed his second five-pointer and completed a treble right at the end, while Miotti finished with 16 points in a rout.
Reds head coach Brad Thorn was unable to celebrate his new contract with a victory as the Bulls ran out 32-17 winners at Loftus Versfeld to go top of the South African Conference.
South Africa fly-half Pollard was the star of the show, scoring 17 points - including a second-half double - as the Bulls showed a great response to their home defeat at the hands of the Jaguares.
Hanro Liebenberg, Marco van Staden and Lizo Gqoboka also dotted down for Pote Human's side.