Victor Matfield (Gallo)

Sydney - South Africa's Bulls, refreshed from last week's bye, look set to keep the heat on their Super 14 title chasers when they host New Zealand's Highlanders on Saturday.

The Bulls head the southern hemisphere provincial championship standings on points differential from last year's finalists the Chiefs, but crucially have a game in hand on all their main rivals after four rounds.

While the Pretoria-based defending champions are favoured to take the points against the Highlanders, the four teams below them are playing each other.

The Chiefs, who missed an opportunity to be sole tournament leaders when they crashed at home to the Reds last week, have a tough New Zealand derby with seven-time champions the Crusaders in Hamilton on Friday.

The third-placed Stormers are at home in Cape Town against fourth-placed Hurricanes on Saturday.

Springbok number eight Pierre Spies is back from injury to bolster the Bulls, who will be led by Springbok lock Victor Matfield for the 50th time in his 99th Super rugby match.

But on the downside, Matfield's lineout partner Bakkies Botha will miss the Bulls' next two Super 14 home games and will also sit out their tour to New Zealand and Australia with an Achilles problem.

Although the Highlanders broke the Bulls' opening five-game winning streak last year, winning 36-12 at home, the Bulls were last defeated at their Loftus Versfeld fortress 23 months ago by the Hurricanes.

The Chiefs have made two changes to their starting lineup against the Crusaders, while also omitting loose forward Sione Lauaki, who has been charged with assault arising from an incident in a Hamilton bar last week.

The Crusaders boast a 10-4 winning record against the Chiefs and four of their wins have been from seven visits to Waikato Stadium, although they lost 18-5 on their most recent visit two seasons back.

"I expect a real lift in our intensity, back to the levels we achieved in the first couple of weeks," Chiefs coach Ian Foster said.

Crusaders coach Todd Blackadder is aware of the Chiefs strikepower out wide and that they will be smarting from surrendering a big lead against the Reds last week.

"We're going up there really committed, really hungry and have focused on looking forward. I'm sure the Chiefs will feel they just need to refocus and it's all there," Blackadder said.

The Hurricanes are looking to the return of midfield backs Conrad Smith and Tamati Ellison to add some composure after they crashed 28-12 to the Central Cheetahs in Bloemfontein last week.

The Stormers were impressive 33-0 winners over the Highlanders at Newlands last week and are hitting form at the right time.

The Cape Town outfit have won seven matches to six against the Hurricanes, but each side has won three of its matches away from home.

Stormers' forwards coach Matt Proudfoot believes his team will have to dig deep to contain the Hurricanes.

"They're very powerful and they look to dominate the contact points, with or without the ball," he said. "The Hurricanes commit numbers at the breakdown, they hit you hard and try and force you out of your structures."

The Sharks, who were unlucky to go down in a tight one against the NSW Waratahs last week, are up against the sixth-placed Brumbies in Canberra on Saturday, while the Waratahs entertain the Golden Lions on Friday.

The Reds will have an Australian derby against the Force in Brisbane on Sunday, while the Blues and Cheetahs have the weekend off.