NSW captain Dave Dennis has suffered a suspected season-ending knee injury in the Waratahs’ Super Rugby derby with the Brumbies in Sydney.

Dennis was helped off ANZ Stadium in a distressed state after falling awkwardly on his right knee following a tackle on Brumbies winger Henry Speight in the 35th minute.

The flanker has already had two knee reconstructions and it would be a cruel blow if he was ruled out for the rest of the Waratahs’ campaign to have a third operation.

The Waratahs are leading the Australian conference with three rounds remaining and are on track for their first finals appearance in three years.