Wellington - Coach Dave Rennie has swung the axe in response to the defending champion Chiefs' shock loss to Australia's Western Force, changing eight of the starting 15 for the Super Rugby clash against the Bulls in Pretoria on Saturday.

The Chiefs went try-less in the 18-15 defeat in Perth, and earned a stinging rebuke from assistant coach Wayne Smith who rated it the worst performance in his tenure with the team.

Rennie appeared to agree, as he cleaned out the forward pack, promoting prop Pauliasi Manu, hooker Rhys Marshall, lock Matt Symons, flanker Tanerau Latimer and number eight Kane Thompson.

The backs feature three changes, with Tim Nanai-Williams benched after experiencing a minor hamstring strain against the Force and replaced by Andrew Horrell.

Winger Anton Lienert-Brown, 18, makes his Super Rugby debut, with veteran Mils Muliaina moving back to fullback.

The Chiefs, back-to-back champions in 2012-3, have not beaten the Bulls at their Loftus Versfeld fortress in over a decade and another loss will put their hopes of a hat-trick of titles in the southern hemisphere competition on shaky ground.

The Chiefs have struggled with their lineout all season and in the Bulls, will battle one of the competition's best at the set-piece.

“It's a huge challenge for our forwards,” Smith told local media. “We've looked for strategies to try to deal with that but it's all about execution in the field.” – Reuters