Topping the table guarantees the Durban outfit a home semi-final and, if successful, they will also host the final.
After taking a hammering in the first match of the season three months ago, Sharks have won 10 consecutive matches as they seek a first title since 2013.
While thunder and lightning temporarily halted them when leading Lions by 11 points at Kings Park stadium in Durban, they quickly regained composure to finish comfortable winners.
Young fly-half Curwin Bosch, capped for the first time by the Springboks this season, contributed 14 points from a conversion, three penalties and a drop goal.
Tries from prop Thomas “The Tank” du Toit and veteran winger Odwa Ndungane completed the scoring for the hosts, who led 11-0 at half-time.
Lions finished runners-up to Canterbury Crusaders of New Zealand in Super Rugby this year, but Springbok call-ups and temporary transfers to Japanese clubs have been disruptive.
Giant winger Anthony Volmink scored a late consolation try which full-back Jaco van der Walt converted after kicking a penalty earlier.
While Sharks have 47 points, fourth-place Lions occupy the last qualifying place with 25, but they are only one point ahead of Pumas and two in front of Blue Bulls.
Pumas had a bye while Bulls scored seven tries and still lost 46-45 to Western Province in a Pretoria thriller between the most successful teams in the 126-year competition.
After 13 tries, a seesaw struggle was decided by a penalty from young Province fly-half Damian Willemse three minutes after the full-time hooter sounded.
World Rugby Sevens star Seabelo Senatla scored twice for Province, making him the leading Currie Cup try-scorer this season with nine.
Griquas shrugged off poor recent form to trounce title-holders Free State Cheetahs 59-24 in northern Cape city Kimberley with the visitors failing to score in the second half.
Cheetahs have lost three of four matches in the South African competition since their best players were chosen for the Pro14 competition.
The Bloemfontein outfit joined Irish, Italian, Scottish and Welsh teams in an expanded competition after being kicked out of Super Rugby.
Dwindling attendances and TV audiences in the southern hemisphere franchise competition led to Cheetahs, fellow South Africans Southern Kings and the Australian Western Force being axed.
Cheetahs lie third behind Sharks and record 33-time champions Province, but need to win one of two remaining fixtures to seal a top-four finish.
The Bloemfontein side host Bulls this Friday and travel to Johannesburg for a showdown with the Lions the following weekend.
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