Hooker Akker van der Merwe and winger Kobus van Wyk scored tries as the Sharks pipped the Melbourne Rebels for the final playoff berth.
Argentina's Jaguares were already assured of seventh-place in the overall table and fielded a side that contained 10 changes as they prepared for a first ever playoff fixture against the Lions in Johannesburg.
The Sharks finished level on 36 points with the Rebels, both sides having won seven matches in the season, but edged their Australian rivals on points difference.
