The previously winless Cheetahs threw the Super 14 play-offs race wide open on Saturday by thrashing fellow South African side the Sharks 31-6.
The Sharks remain top of the table with 30 points from nine matches but they had opened up a three-point lead on the ladder and, with five of their final six games at home in Durban, were expected to canter into the semi-finals.
The Bulls move into third above the New South Wales Waratahs on points difference after the South African side became the first Super 14 team to win at the Sydney Football Stadium since 2007.
The Chiefs are now just three points back in second, despite not playing this weekend.
But the Waikato franchise has possibly the toughest run into the finals of the five New Zealand sides - the Chiefs play the Cheetahs, the Bulls and the Stormers in South Africa before returning to play home games against the Hurricanes and the Brumbies.
The other New Zealand sides all sit just outside the semi-final places.
The Hurricanes are fifth with 24 points and have arguably the easiest run-in: three home games in a row against the Stormers, Brumbies and Blues before the Wellington-based team finish on the road against the Chiefs and the Queensland Reds.
The sixth-placed Blues are a point back and have two home games against the Highlanders and the Reds coming up before tough away games against the Hurricanes and the Brumbies. Their last pool game's at home against the Crusaders.
In seventh the Highlanders have 22 points and seemingly little chance of a top four spot - four out of five of their games are on the road. They play the Blues at Eden Park this week before their last home game against the Stormers. Then it's the Sharks, the Lions and the Force away.
The Crusaders are just behind the Highlanders on points difference and also face four out of five remaining games on the road. They play the Sharks this weekend, who will be hurting after Saturday's result.
The Crusaders' South African trip concludes with the Cheetahs and the Lions. Then it's the Reds at home and the Blues in Auckland.