NSW coach Chris Hickey remained optimistic about the injury-ravaged Waratahs Super Rugby finals hopes, despite a 23-17 loss to the Bulls and incurring several more casualties.

The result in Pretoria on Saturday morning (AEST) enabled the defending champions to leapfrog NSW into fifth place on 49 points.

NSW dominated possession, but couldn't convert enough opportunities and played the last 13 minutes with 14 men, after replacement lock Pat O'Connor was sent off for an alleged head butt.

Television footage of the incident appeared inconclusive and Hickey expressed reservations about the decision, but O'Connor was scheduled to front a judiciary on Saturday evening (AEST).

Another Waratahs lock, Kane Douglas, was cited to appear before the judiciary for an alleged dangerous tackle, after allegedly grabbing Bulls centre Wynand Olivier in a headlock.

Already without captain and flanker Phil Waugh, No.8 Wycliff Palu, winger Drew Mitchell, prop Sekope Kepu and centres Rob Horne and Ryan Cross, NSW lost four more players inside the first 50 minutes.

Prop Benn Robinson and No.8 Ben Mowen (ankle), winger Lachie Turner (hamstring) and replacement prop Paddy Ryan (AC joint) joined the lengthy injury list.

Hickey said Robinson, who lasted just 18 minutes, was in doubt for next Saturday's critical home clash with the eighth-placed Highlanders, but the extent of all four injuries wouldn't be known until the casualties had scans after returning home.

The Bulls scored two tries to one, but a bonus point moved NSW onto 47 points, level with the Sharks, who were scheduled to play the Cheetahs in Bloemfontein early on Sunday (AEST).

And Hickey knows NSW cannot afford another defeat in their two remaining games at home to the HIghlanders and Brumbies.

"The Stormers, the Bulls and the Sharks have got all got to play each other over the next three weeks, so it just means we start to ride other teams results, which you prefer not to," Hickey told AAP.

"But I still feel think if we can take care of our own games against the Highlanders and then the Brumbies I'm still reasonably optimistic that the other results may flow our way and get us into that top six spot."

Both teams kicked two penalties before converted tries to Olivier and winger Bjorn Basson in six minutes either side of halftime gave the Bulls a 20-6 lead.

NSW battled their way back to within three points after scoring the next 11, from two penalties to fullback and man-of-the-match Kurtley Beale and a try to replacement winger Atieli Pakalani.

Five-eight Morne Steyn gave the Bulls some breathing space by kicking the penalty awarded for O'Connor's transgression.

Beale cracked the Bulls defence with a chip and regather in the closing minutes, but NSW couldn't finish off the opportunity.

"I'm certainly proud of the effort and the character that the team showed in difficult circumstances," Hickey said.

"If you are going to look at our performance critically, you'd say we had quite a few possessions in the Bulls 22 and we failed to complete them for points."

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