Super Rugby leaders the Sharks have all but ended the Blues' playoff hopes and extended their lead in the competition after the South Africans won 29-23 at North Harbour Stadium.
Both sides scored two tries but it was the Sharks' defiant defensive performance that gave them their 10th straight victory over the Blues.
Tries from skipper Bismark Du Plessis and halfback Cobus Reinach, and 16 points from the boot of Francois Steyn, kept the visitors ahead on the scoreboard but it was their defence that won them the game, despite two yellow cards.
The Blues, who had been unbeaten at home this season, enjoyed the majority of possession and matched the Sharks' try count with scores from flanker Luke Braid and winger Tevita Li but were unable to break through in a tense last 10 minutes.
After their equally impressive victory over the Crusaders with 14 men last week, the Sharks will return to Durban clear leaders in the South African conference and already almost certain of a place in the playoffs.