Cape Town - The Bulls have stretched their lead atop the South African Conference with victory over the Waratahs in their Super Rugby clash in Sydney on Friday.

Werner Kruger scored a 78th-minute try to push the Bulls past the Waratahs to all but end the home side's playoff hopes.

Prop Kruger rolled over beneath a pile of players to plant the ball over the line and secure the Johannesburg-based side's eighth victory of the season, cementing top spot in the South African conference of the southern hemisphere provincial competition.

"It's always tough coming to Sydney," Bulls captain Pierre Spies said in a pitchside interview. "We had to fight it out to the end. I'm very proud of the team.

"When you're playing away from home you need that defence... We're going to enjoy tonight and re-focus on Monday."

The late try was a cruel blow for the Waratahs who dominated possession and territory for most of the night but wilted under pressure in the final minutes.

The Waratahs were left trailing local rivals ACT Brumbies by nine points, with the Canberra-based side holding a game in hand and in the box seat to secure an automatic spot in the playoffs at the top of the Australian conference.

The Waratahs led 13-10 at halftime and held a 24-20 lead in the final minutes but failed to land the knockout punch as they slumped to their seventh loss of the season.

Outside centre Rob Horne came back from a two-game suspension to score a try in the 16th minute, streaming through a hole in defence to cross left of the posts after taking a flat pass from Berrick Barnes outside the 22-metre line.

Lock Dean Mumm undid the Waratahs' good early work by getting sent off seven minutes later for a dangerous line-out infringement and Bulls scrumhalf Francois Hougaard instantly made the home side pay.

The barrel-chested Hougaard took the ball from a ruck and embarrassed the Waratahs' defence by shrugging off a two-pronged tackle by prop Benn Robinson and captain Rocky Elsom near the try-line, then shoving opposing scrumhalf Sarel Pretorius over to score the Bulls' first try.

Barnes slotted a penalty goal shortly after halftime to put the Waratahs 16-10 up, but the Bulls ratcheted up the pressure towards the end of the third quarter.

After repelling wave after wave of attacks on the line, the Waratahs' defence succumbed in the 59th minute when the ball was spread wide to Morne Steyn who fed winger Akona Ndungane for the Bulls' second try.

Steyn's conversion put the Bulls in front for the first time in the match, but Barnes stole back the momentum four minutes later with a long, looping pass to the right that beat a lone Bulls defender and allowed winger Atieli Pakalani to charge over from 10 metres out.

Morne Steyn, who finished with 12 points after another flawless night with the boot, slotted home his second penalty before Brendan McKibbin answered late to give the hosts a precarious four-point lead.

A defensive error on the last line of defence cost the Waratahs dearly, however, as they lost the scrum in the final minutes and were powerless to prevent Kruger barging over with support from the forwards.

Teams:

Waratahs:
15 Daniel Halangahu, 14 Tom Kingston, 13 Rob Horne, 12 Adam Ashley-Cooper, 11 Atieli Pakalani, 10 Berrick Barnes, 9 Sarel Pretorius, 8 Wycliff Palu, 7 Chris Alcock, 6 Rocky Elsom (captain), 5 Kane Douglas, 4 Dean Mumm, 3 Sekope Kepu, 2 John Ulugia, 1 Benn Robinson
Substitutes: 16 John Mann-Rea, 17 Jeremy Tilse, 18 Sitaleki Timani, 19 Lopeti Timani, 20 Dave Dennis, 21 Brendan McKibbin, 22 Tom Carter

Bulls:
15 Zane Kirchner, 14 Akona Ndungane, 13 Johann Sadie, 12 Francois Venter, 11 Bjorn Basson, 10 Morné Steyn, 9 Francois Hougaard, 8 Pierre Spies, 7 CJ Stander, 6 Deon Stegmann, 5 Juandré Kruger, 4 Flip van der Merwe, 3 Werner Kruger, 2 Chiliboy Ralepelle, 1 Dawie Steyn

Substitutes: 16 Willie Wepener, 17 Rayno Gerber, 18 Wilhelm Steenkamp, 19 Arno Botha, 20 Jano Vermaak, 21 Louis Fouché, 22 JJ Engelbrecht