The Stormers snatched a 26-28 Super Rugby victory from the Blues with a late converted Schalk Burger try in Auckland on Friday.
The victory is the Stormers ninth of the season and puts pressure on the Sharks and the Bulls who face each other in the South African conference later this weekend.
The Stormers outscored the Blues by three tries to two.
The Blues led for almost the entire match after Luke McAlister kicked a penalty in the first minute of the game.
Trailing 19-3 at half time the Stormers looked like they were out of the match but scored two quick tries in the space of three minutes in the final quarter to put the Blues under pressure.
As the match neared the end the Stormers were awarded a penalty and kicked for the corner. They won the line out and used the maul to drive over for the try which leveled the scores.
Scrum half Dewaldt Duvenage who came on to replace injured fly half Lionel Cronje in the first half had the task of kicking the conversion to win the match and held his nerve by slotting the match winning conversion.
The match was almost an exact opposite of the Stormers' last match against the Chiefs last week when the Stormers led 20-3 at halftime but conceded three second-half tries to lose 30-23 to the Chiefs.
The Stormers trailed at halftime but scored three second-half tries, including Burger's in the 79th minute
Stand-in centers Juan de Jongh and Johann Sadie combined for two tries in three minutes in the middle of the second half .
The win was of critical importance to the Stormers after their back-to-back losses to the Crusaders and Chiefs.
Those defeats saw their season-long lead in the South African conference placed under threat from the Sharks, who can still challenge for first place when they play the Bulls in Durban on Saturday.
But the Stormers gave themselves a measure of comfort - a five-point conference lead - with a rousing second-half rally in a match which seemed to have been lost through a torrent of errors in the first half.
The Cape Town-based side turned the ball over continuously by trying to play over-ambitious rugby in wet and slippery conditions.
Their poor handling and lack of discipline allowed the Blues to take control of the match with a try to halfback Alby Mathewson and 14 first-half points to center Luke McAlister.
McAlister surpassed 100 points for the season - becoming the first New Zealander to do so this year - with the second of his four penalties.
He finished with 16 points for the match, enhancing his chances of a recall to the New Zealand team for this year's World Cup.
Mathewson scored the only try of the first half and fullback Lachie Munro scored in the 67th minute after tries by De Jongh and Sadie cut the Blues' lead from 19-3 at halftime to 19-18 midway through the second half.
Munro's try gave the Blues the buffer of an eight-point lead with 13 minutes remaining but Duvenage reduced that with a 70th-minute penalty then decided the match with the conversion of Burger's last-gasp try.
The win was a triumph for a Stormers team reduced in strength by injuries to first-choice flyhalf Peter Grant and centers Jean de Villiers and Jaque Fourie.
They suffered a further blow when they lost replacement flyhalf Lionel Cronje to a knee injury after 28 minutes.
But Duvenage took Cronje's place and made a vital contribution, kicking two conversions and two penalties from five shots at goal.
Blues captain Keven Mealamu became New Zealand's most-capped Super rugby player in a match his team could have marked with a win.
The Blues are now left with a record of nine wins from 13 games and their lead in the New Zealand conference is under threat from the Crusaders.
Final Score Blues 26 Stormers 28
Tries - A Mathewson, L Munro
Pen - L. McAlister 4
Con - L McAlister 2
Tries - J de Jongh, J Sadie, S Burger
Pen - L Cronje, D. Duvenage 2
Con - D.Duvenage 2
Cards - Francois Louw (32nd min) Yellow
Referee: Keith Brown
Ass. Ref. 1: Glen Jackson
Ass. Ref. 2: Richard Kelly
TMO: Ben Skeen
Blues :1. Tom McCartney,2. Keven Mealamu (Capt),3. John Afoa,4. Anthony Boric,5. Ali Williams,6. Jerome Kaino,7. Luke Braid,8. Peter Saili,9. Alby Mathewson,10. Stephen Brett,11. Sherwin Stowers,12. Luke McAlister,13. Jared Payne,14. Joe Rokocoko,15. Lachie Munro
Replacements :16.Pauliasi Manu (FR),17.Tevita Mailau (FR),18.Chris Lowrey,19.Sean Polwart,20.Chris Smylie,21.Winston Stanley,22 .Rene Ranger
Stormers :15. Conrad Jantjes,14. Gio Aplon ,13. Johann Sadie,12. Juan de Jongh,11. Bryan Habana,10. Lionel Cronje,9. Ricky Januarie,8. Duane Vermeulen,7. Francois Louw,6. Schalk Burger (Capt),5. Andries Bekker,4. Rynhardt Elstadt ,3. CJ van der Linde,2. Deon Fourie,1. Wicus Blaauw
Reserves :16. Tiaan Liebenberg,17. Brok Harris,18. Steven Kitshoff,19. Anton Van Zyl,20. Dewaldt Duvenage ,21. Danie Poolman,22. Nick Koster