Blues coach Sir John Kirwan has conceded his side's hopes of making Super Rugby's play-offs are virtually over after their 29-23 loss to the Sharks.

The defeat, their seventh of the season, leaves them firmly rooted to the bottom of the New Zealand conference and 10th overall with games against the Hurricanes, Force, Crusaders and Chiefs to come.

"We needed tonight to take a bit of pressure off," Kirwan told Radio Sport. "We are really under the pump. We've sort of been keeping our head above water all year and haven't really had a break from that. But now it's pretty desperate really."

The Sharks, who cemented their place at the top of the overall standings with the win, accumulated points steadily in the first half, profiting from Blues mistakes and poor discipline to take a 16-6 lead at the break. But it was their defence in the second half - where they only conceded tries to Luke Braid and Tevita Li when they had Jannie du Plessis and then Francois Steyn in the sin bin - that got them their victory.

The majority of the Sharks points came predictably from the boot of Steyn, who finished the game with three penalties, two conversions and a drop goal for a 13-point haul.

Bismarck du Plessis and Cobus Reinach got a try in each half with SP Marais adding a penalty when Steyn was cooling his heels on the sideline. It was Reinach's try, which came when the Blues lost the ball at the ruck after finally gaining some traction with ball in hand, which effectively sealed the New Zealanders' fate.

"We were hanging on to multiple phases and thought we'd done enough to win it at times," lamented Kirwan. "But a couple of dumb penalties and a soft try and the game's gone."