The Stormers strengthened their position atop the South African Super Rugby conference with a 27-17 victory over the Lions at Newlands.
The win gave the Stormers 58 points, four behind overall leaders the Chiefs and nine ahead of their nearest South African challengers.
They were made to work hard against a Lions team which went into the match having claimed just two victories in this year's competition.
The unfancied Lions trailed by three points with 10 minutes left before two tries in a six-minute spell ended their hopes.
""We weren't good enough at the breakdown," Stormers skipper Jean de Villiers said in a pitchside interview. ""We need to improve a lot but I'm happy with the win."
The Stormers edged into a 6-3 lead after 27 minutes thanks to two penalties from flyhalf Peter Grant, the Lions replying with a penalty from Elton Jantjies.
The first try came after 30 minutes when Stormers wing Danie Poolman made a searing midfield break and fullback Gio Aplon landed his sixth try of the season.
Grant added the conversion as the Stormers went to the break 13-3 up.
The Johannesburg-based Lions began the second half the strongest and, eight minutes in, narrowed the deficit when flanker Josh Strauss burst clear from a ruck before setting off on a 22-metre run on his way to a converted try.
The Stormers hit back with 10 minutes left, Canadian international loose forward Jebb Sinclair forcing his way over in the corner for a converted try.
The score seemed to knock the stuffing out of the Lions and the Stormers claimed another try when winger Gerhard van den Heever jinked his way over from 10 metres out.
There was a late consolation try for the Lions when lock Franco van der Merwe dived over.
""Our discipline let us down especially in the first half," said Lions captain Strauss.
""Our scrum and our driving play was good but if we had not given away so many penalties it could have been a different game."
