The NSW Waratahs have suffered one of their most embarrassing defeats in Super Rugby history, falling 26-3 to the lowly Cheetahs at the Sydney Football Stadium.

Second-half tries to winger Phillip Snyman and replacement Sarel Pretorius, plus two conversions and three penalty goals from first five-eighths Sias Obersohn earned the touring South Africans their first-ever Super win in Australasia - and first win at all in 2011.

A 30th-minute penalty from fullback Kurtley Beale was the only offering in another clumsy display from the Waratahs, who had been desperate to get their campaign back on track following last week's bye and a round-three loss to the Crusaders.

MATCH STATS
SUPER 15 STANDINGS

Disgruntled fans either booed their side at fulltime or began filing out of the ground early as the Waratahs recorded their lowest points total at home in 16 years of Super Rugby.

Compounding the Waratahs' misery was an apparent rib injury to Benn Robinson that forced the Wallabies prop off after just 17 minutes.

Few would have predicted the Cheetahs' historic victory in the opening minutes when the Waratahs came out firing, creating several scoring opportunities with Beale and returning first five-eighths Berrick Barnes looking particularly threatening.

Alas, the Tahs were unable to convert their early dominance into points and were made to pay in the second half.

"We just didn't perform basically," stand-in captain Dean Mumm said.

"It's disappointing, that's all I can say."

The Waratahs faithful must have sensed it wasn't going to be their night when flanker Pat McCutcheon - filling the enormous boots of 126-game captain Phil Waugh - spilt the ball with the line beckoning with a half-hour remaining.

After a great bust from fellow backrower Dave Dennis, all McCutcheon had to do was collect the final pass and stroll five metres - but, to gasps of disbelief, he dropped the ball cold.

The Tahs only trailed 9-3 at that point, but the writing was on the wall.

The demoralising defeat adds even greater significance to next week's Australian derby with the Brumbies in Canberra.

"We've got to move forward," Mumm said. "We've got a lot of work to do."

CHEETAHS 23 (Sarel Pretorius, Philip Snyman tries Sias Ebersohn 2 cons 3 pens 2 drop goals) bt NSW WARATAHS 3 (Kurtley Beale pen) at Sydney Football Stadium. Referee: Chris Pollock. Crowd: 15,849

- AAP