Cowan ready to rise to Springbok challenge for Scotland
Cowan was in Vern Cotter's initial training squad for the tournament but was then left out of the final group as the coach opted to select just one openside flanker in John Hardie.
But, following a groin injury to lock Grant Gilchrist, Cowan has been handed a second chance ahead of Saturday's meeting with South Africa at St James' Park, which will likely decide the winner of Pool B.
Insisting he has no hard feelings towards fellow New Zealand-born player Hardie, Cowan said: "I was really impressed by John in the Japan game. He played extremely well. He was very physical and put in a truck load of work.
"I got on really well with 'Hards' during pre-season and before I left I wished him all the best. I think he proved why Vern put him in the squad with that first game.
"He and I have slightly different games and I won't be trying to outdo what he does, because that's his thing and he's very good at it. But I'll be trying to lift the level of what I do.
"The [coaches] know what I can do. I don't need to prove myself. I just want to come up here and be positive. Even if it's just in training, I'll just bring some energy.
"And if I'm called up to play on Saturday am I ready? Yeah - just show me the jersey.
"It was devastating [to be left out of the initial squad]. So to get the call-up is sensational. It's every man's dream. It's just a shame it comes on the back of someone hurting themselves."