The Sharks clung on for a 31-27 win over the Highlanders to make the Super Rugby semifinals on Sunday.
The Highlanders threw everything at it, twice coming from behind to lead before ultimately being denied in the final minutes.
Despite holding forward dominance throughout the playoff at Kings Park, the Sharks were trailing with seven minutes to go and needed two late penalties by first-five Frans Steyn to take their place in the last four.
The home team twice lost the lead and control of the game to the Highlanders' lethal backline attacks, which produced three tries and nearly a repeat of the visitors' surprise win in Durban during the regular season.
Steyn kicked his game-deciding penalties in the 74th and 79th minutes after the Sharks' forward power finally paid off - but only just.
"I must say they ran us to pieces at some stages," Sharks captain Bismarck du Plessis said.
"Their whole backline was absolutely amazing."
The Sharks led 10-0 and were in complete control, but the Highlanders scored two tries at the end of the first half through All Blacks centre Malakai Fekitoa and prop Kane Hames to turn it around at 17-13.
The Sharks pushed ahead 25-20 in the second only for another superb backline try when wing Patrick Osborne and centre Phil Burleigh combined to put the Highlanders within reach of an upset win.
Sharks replacement flanker Jean Deysel lost the ball on the tryline in the 72nd minute as the home team launched a succession of close-quarters, forward-dominated attacks.
The attacks earned a penalty soon after and Steyn gave the Sharks the lead for the third and final time.
He added his fourth successful penalty with barely a minute left to make it certain, and finally end the season for the resilient Highlanders.
"I'm just proud of our character ... we did ourselves justice tonight," Highlanders fullback Ben Smith said.
Sharks 31 (Marcell Coetzee, Bismarck du Plessis, Tonderai Chavhanga tries; Frans Steyn 2 conversions, 4 penalties)
Highlanders 27 (Malakai Fekitoa, Kane Hames, Phil Burleigh tries; Lima Sopoaga 3 conversions, 2 penalties). HT: 13-17.