JOHANNESBURG, SOUTH AFRICA - APRIL 12: Lwazi Mvovo of Sharks charging past Willie Britz of Lions to score his try during the Super Rugby match between Lions and Cell C Sharks at Ellis Park on April 12, 2014 in Johannesburg, South Africa. (Photo by Gallo Images)

Sydney – The Sharks begin a testing tour of Australasia this weekend bidding to hang on to their tenuous Super Rugby lead with the ACT Brumbies and Wellington Hurricanes waiting to pounce.

Jake White's Sharks lead the southern hemisphere provincial competition by just one point after they were upset at home by the Otago Highlanders last week.

The Sharks, who have played seven of their opening nine games at home this season, take on the Rebels in Melbourne on Friday in the opening match of a four-game tour which will have a large bearing on their playoff chances.

If the Durban-based outfit slip up, the Brumbies could take over at the top with a win over the much-improved Canterbury Crusaders with All Black skipper Richie McCaw back in action in Christchurch.

The third-placed Hurricanes, who have displaced defending champions Waikato Chiefs at the top of the New Zealand conference, can also pressure the Sharks if they beat the NSW Waratahs in Sydney on Saturday.

“We want to bounce back. It doesn't matter who it is, it's not the Rebels we're targeting,” White said.

“When we lost to the Bulls, we won the next game against the Waratahs. This week we need to make sure that regardless of who we're playing, we need to be better than we were last week to get a result.”

On last season's tour, the Sharks lost three of their four games and traditionally, overseas trips have proved the downfall for South African sides.

“We want to get our tour off to a good start and take momentum through the tour and in order to do that we need to get a win in the first game,” White said.

The Crusaders will prove a tough obstacle for the in-form Brumbies with the return of the inspirational McCaw from a broken thumb.

McCaw's return helps offset the loss of skipper Kieran Read with concussion he suffered in last week's win against the Chiefs.

The seven-time Super Rugby champions have won their past three matches and have not lost at home to the Brumbies since 2000.

“After a shaky start to the season they've found some form and will be further boosted by the return of Richie McCaw,” Brumbies coach Stephen Larkham said.

The Waratahs have made three changes, among them the return of Wallaby number eight Wycliff Palu, for the visit of the rejuvenated Hurricanes.

The Sydneysiders were disappointing in losing to the Blues 21-13 in Auckland last week and coach Michael Cheika has reacted in a bid to keep the Waratahs in playoff contention.

Cheika has problems of his own and was hit with a suspended six-month ban this week by SANZAR for abusing a cameraman during the Australian team's March loss to the Sharks in Durban.

The Hurricanes, in the top three spots as a national conference leader, have been stable under coach Mark Hammett, who has made just one change to his starting team in his two previous team announcements.

Last week the Canes scored five tries in beating the Queensland Reds 35-21 and have won their past four games.

“They're certainly playing some really good football. The Hurricanes have changed their style of attack and how they go about things and it seems to be working for them,” Waratahs centre Adam Ashley-Cooper said.

“For us, it's a really big game. We're at home, we need to win. Obviously it wasn't the result we wanted last week and I feel this game could define our season.”

In the weekend's other games, Auckland Blues host the Reds, the Chiefs have home advantage over the Lions, the Bulls face the Cheetahs in Pretoria and the Stormers are at home to the Highlanders.

Western Force have a bye. – Sapa-AFP