Lions replaced Sharks at the top of the Africa 2 Super Rugby Conference with a 24-9 derby victory at Kings Park on Saturday.
Sharks were beaten by Crusaders last time out and came unstuck once again for a second successive home game, only mustering three Joe Pietersen penalties in Durban.
Andries Ferreira and Lionel Mapoe scored the only tries of the game in the first half, while Elton Jantjies booted 14 points as Lions responded to their defeat by Crusaders with what could prove to be a crucial victory.
Lions got the upper hand in the opening stages and Jaco Kriel had a try ruled out for a forward pass before Ferreira crashed over four phases after making a burst down the centre to put Sharks on the back foot.
Jantjies converted and was successful with two penalties before Mapoe went over for a second try eight minutes before half-time, with handling errors costing Sharks as a couple of Pietersen penalties was all they could come up with in the first half.
Pietersen reduced the deficit to 18-9 from the tee just after the break, but Jantjies added another two penalties to increase Lions' advantage and reward a dominant display from their forwards.
Lions were unable to claim a bonus-point try, but are now two points better off than Sharks - who must now regroup as they prepare to start their tour at Blues next weekend.