Wellington - The Sharks face being toppled as Super Rugby leaders this weekend with the Waratahs and Crusaders both having a golden opportunity to overtake them.
While all South African teams have a bye as the Springboks play Scotland, it opens the way for a change at the top in the tightly packed competition where only five points separate the leading four teams.
The Australia and New Zealand conferences resume after their June Test window with the second-placed Waratahs, just two points behind the Sharks, eyeing the outright lead if they put away the Brumbies in Sydney on Saturday.
However, a slip by the Sydneysiders would gift the lead to the Crusaders, four points in arrears, if they beat the Hurricanes.
In the battle to fill out the top six, the fourth-placed Brumbies and sixth placed Hurricanes are in a must-win situation as they both have a bye in the remaining three rounds.
Close behind them, the seventh and eighth-placed Western Force and defending champions Chiefs are in line for promotion to a play-off position if they win and other results go their way.
Waratahs coach Michael Cheika has made just one change to the starting side that beat the Chiefs in their last outing four weeks ago, with Wallaby prop Sekope Kepu starting at tighthead in place of Paddy Ryan.
The win over the Chiefs completed a successful four-week run into the Test break for the Waratahs with Israel Folau moving to 11 tries for the season, four more than his nearest challenger.
Cheika admitted it was impossible for the dozen Waratahs involved in the Wallabies' 3-0 whitewash of France not to have taken a little time to savour last Saturday's big third Test win.
“But I trust my guys to understand what's at stake,” he said.
“The key is to make sure they understand where the moments are in the game that they need to take advantage of, how can they recognise the opportunities.”
Although the Brumbies have a mathematical chance of getting to the top, their more immediate target with a win over the Waratahs would be a return to the head of the Australian conference.
The seven-time Super champion Crusaders head to Wellington for their clash with the Hurricanes with both sides suffering from the effects of the All Blacks' physical Test series against England.
The Crusaders will be without their talismanic flanker Richie McCaw, who has a broken rib, while the Hurricanes are without centre Conrad Smith who broke a thumb.
But the Crusaders do benefit from the return of Kieran Read and Dan Carter off the bench, with fly-half Carter having his first Super game since taking a six-month holiday at the end of last year.
The Chiefs open the weekend away to the fifth-placed Otago Highlanders with both sides acutely aware they need a win to keep their play-off hopes alive.
Of the remaining weekend matches, the Force play the Auckland Blues and the Melbourne Rebels face the Queensland Reds.
Only the Force have a realistic chance of finishing in the top six, but they must first beat the Blues who have not won away from home since the start of last year.