CHRISTCHURCH, NEW ZEALAND - MAY 17: Sharks team mates celebrate after the round 14 Super Rugby match between the Crusaders and the Sharks at AMI Stadium on May 17, 2014 in Christchurch, New Zealand. (Photo by Martin Hunter/Getty Images)

Sydney - The NSW Waratahs can clinch a home semi-final with victory over the Otago Highlanders while the pressure is on the Coastal Sharks to win a crunch South African derby in this weekend's Super Rugby.

The Waratahs are three points clear of the Sharks heading into the penultimate regular round to decide the top-six play-off spots and are chasing their sixth straight win.

The Sydneysiders, who are bidding for their first Super Rugby title after finishing runners-up in 2005 and 2008, can lock up a top-two berth and with it a home semi if they can beat the Highlanders in Sydney on Sunday.

The Highlanders are lying fourth overall but are joint leaders of the New Zealand conference with the Canterbury Crusaders with only points differential splitting them.

Otago stormed into finals' contention with a 29-25 win over defending champions Waikato Chiefs last weekend and are looking to improve on their record over the Tahs where they have won two on their last four trips to Sydney.

“To nullify their threats and to maintain ours, you're going to have to be working hard all the time because of the way we want to play the game,” coach Michael Cheika said.

“You don't want to kick them the ball too much and if you're not going to be kicking the ball too much, you have to run with it, work hard.”

The Highlanders will have to be at their very best to knock over the Waratahs where they haven't been beaten at home this season, coach Jamie Joseph said.

“We are coming into the business end of the season and all teams have to stand up,” Joseph said. “They are a big, strong side up front and have a lot of X factor.

“Any team that can put 30 to 40 points on the Brumbies last week must be a good side.”

Jake White's Sharks face a big test in Bloemfontein on Saturday to stay in the hunt for a top-two spot.

The Durban franchise were overtaken by the Waratahs at the top of the table last weekend and Central Cheetahs coach Naka Drotske says the heat is on the Sharks.

“I think all the pressure is on them. They are still in the running for the title and, if they want to host a home semi-final, they need to win their next couple of games,” Drotske said.

“In South African derbies anything can happen and we look forward to the game.”

The Sharks were sailing along at the top until they were ambushed by the Western Stormers 21-19 at home at their last start and have the pressure of winning in Bloemfontein.

The Sharks have a strong record in the High Veldt, winning four of their five games against the Cheetahs.

“The way things stand, if we can win both games then we'll have a home semi-final,” Sharks prop Lourens Adriaanse said.

“So the next two games are very important for us.”

Seven-time champions Canterbury Crusaders, trailing the Waratahs by six points, have chosen a strong combination for their match with the Auckland Blues in Christchurch on Saturday.

All Blacks ace Dan Carter will make his first start of the season in an unfamiliar role at inside centre while No.8 Kieran Read and prop Owen Franks will be in the run-on team along with fullback Israel Dagg.

“Training this week has felt like the lead-up to a final,” coach Todd Blackadder said. “There was a huge amount of disappointment and frustration following last week's loss, but we've had to push that aside.”

In other finals-bearing games, Wellington Hurricanes must beat the Chiefs in Hamilton, while Western Force need to get past the Queensland Reds at home.

Elsewhere the Stormers are at home to the Northern Bulls and the Golden Lions host the Melbourne Rebels.