Waratahs captain Dave Dennis says he was bitterly disappointed to miss out on Michael Cheika's 31-man Rugby World Cup squad but will use that as motivation to continue the Sydney Stars' unbeaten start to the National Rugby Championship.

Dennis played 18 Tests in as many months after his debut in June 2012, but faced a major setback after rupturing his right anterior cruciate ligament last year just weeks before the Waratahs' breakthrough Super Rugby victory.

The 29-year-old has returned to the field, starring for both the Waratahs and the Sydney Stars, but was not in Cheika's plans for the World Cup which starts in two weeks. "It's hugely disappointing," Dennis said. "I missed out in 2011 over in New Zealand and I missed out again this year. It's really disappointing but there's not much you can do, you've got to keep working hard."

Dennis has no hard feelings towards Cheika and said he would be watching all the action from home. "I've got to get on with it I suppose," Dennis said. "He [Cheika] gave me his reason which I respected around the positioning and where he saw me in the team. It's only a 31-man squad so it's pretty tight ... there's guys who missed out for similar reasons so he communicated that with me."

The Sydney Stars, however, will be without Dennis for this weekend's clash with Perth Spirit at Leichhardt Oval because he is attending a wedding. They have won both their games this season - twice as many as they did last year - but the memories of last season's 63-21 thrashing at the hands of Perth will be in the back of their mind, according to Dennis.

"The whole mindset and attitude is a whole lot different in terms of the playing group, but in the short history of the competition there are still things that you remember," Dennis said. "Even the Queensland Country game at Balmain, the boys spoke about how they lost by 40 to them up in Queensland, so those things still hang around. But there's a really positive feeling in the group at the moment and we're really just focused on keeping the winning streak going."

Stars prop Tom Robertson - the competition's leading try-scorer - will be looking to extend his three-try tally and continue to prove to Dennis that he can make the step up to Super Rugby in the next few years.

"He's got the ability to play both sides of the scrum which is not easy to do," Dennis said. "You don't lead the try-scoring as a prop if you haven't got some ability. He's the perfect example of what this competition is about. Of the young guys who could go on to play Super Rugby, I think he's one of them."

Former Waratahs player Tom Carter will make his return from injury in the game.