IT would be the understatement of the century to say that things have not always gone smoothly in Chris Cusiter's rugby life.

The scrum-half, who shot to prominence with the Border Reivers a dozen years ago, has had more injuries than you would witness in a particularly lurid episode of Casualty, and he has had to fight tooth-and-nail for his Scotland place against a cast of rivals who have included Mike Blair, Rory Lawson, Greig Laidlaw and Henry Pyrgos.

In which light, it speaks volumes for his tenacity and durability that the 32-year-old can now reflect on an international career in which he has still managed to clock up 70 appearances for his country. Not that he was in a particularly reflective mode as he sat down to talk at BT Murrayfield yesterday, for it was easily seen that this most determined of players was still reeling from the hurt of being left out of the original Six Nations Scotland squad named by coach Vern Cotter last month.

Cusiter has dealt with most of the slings and arrows his sport can dish up, but his myriad misfortunes had never included being omitted from a national squad on form, rather than injury, before. When the call came through from assistant coach Duncan Hodge, Cusiter was so shaken by the experience that he sat down in his kitchen, alone with his thoughts, and did not move for 45 minutes.

But then the old Cusiter kicked in. The bristling pride and feistiness - qualities that are so obvious on the pitch but almost inconspicuous in his humble off-field persona - returned to ensure that he would wallow in self-pity no longer. "For me, it has always helped to have that underdog thing going on," he explained. "I thought, 'Right, I'll tell you what. I'll play as well as I can so you have to pick me'. It does strengthen your resolve, for sure."

In fairness, his return to the squad has a precautionary element. Sam Hidalgo-Clyne, the current back-up scrum-half to Laidlaw, is presently going through concussion recovery protocols and Cusiter is really only there to provide cover if Hidalgo-Clyne does not come through that process. Yet he is clearly minded to make the most of his opportunity and remind Cotter what a valuable player he can be.

Inconveniently, goal-kicking cannot be counted among his attributes. By contrast, Hidalgo-Clyne's abilities in that area have earned him the nod as he provides a seamless transition if or when he takes over from Laidlaw in the course of a match. Pyrgos can also step up to that plate if required, so Cusiter knows he is at a disadvantage.

But still the fire burns. Cusiter had an unhappy World Cup in 2011 - having just fought his way back from a lengthy injury absence, he made just two brief appearances off the bench in New Zealand - an experience that fired his determination to be more involved this year. As he admits, though, the emergence of other scrum-half options means he has a real fight on his hands to remain in the Scotland reckoning.

"I know I am getting older," he said, almost poignantly, at one point. "Things move on. I am 32 and there are not that many guys playing international rugby who are above 30. It is a young man's game. But if you are fit and playing well and regularly you always think you have a chance.

"But yes, [the World Cup] is a big goal. I really would like to play a big part in the tournament, not just be part of the squad. Last time, I was just coming back from injury so I wasn't in a great position to state my case. I still feel that things can change and I can play a big part.

"You have to have goals. It's important to have them to keep you pushing forward and motivated and that is one of mine. If I keep training hard and stating my case then we will see what happens."

It is not impossible, of course, that Hidalgo-Clyne will tick all the medical boxes over the next day or two and Cusiter will be sent back down the road to Sale. It may be that his Scotland career is over already. But you dismiss him at your peril. Cusiter is one of just three Scots still playing - the other two are Ross Ford and Richie Gray - who have appeared in a Test for the Lions and he is certainly not one for giving things up easily.

"If you are around long enough in this game then you will have disappointments and setbacks," he said. "You've just got to get back on the horse and be determined to get back involved."