After a post-tour dip in form prompted by a wrist injury and increased expectation, Roberts is now back to his very best and Barnes knows he will have to produce an impressive defensive performance to stop the Blues big-man from running riot in Cardiff.
''I was lucky enough to get the chance to play against Wales in the third-placed World Cup play-off, and it would be great to go up against them again. I'd also love another chance to come up against Jamie Roberts,'' said Barnes, a silky smooth playmaker who could well face Roberts once more when the Lions head Down Under in 2013.
"Jamie is a physical player. There are guys that you tackle who are big and imposing blokes. He is hard, he is bones, he is muscle and a tough man to tackle.
"He runs extremely good lines and is a talisman for Wales and, when he does well, they tend to get momentum off that.
"They have speed, too, which is a bit daunting for someone like me who is only 90kgs as well."
And while the Wallabies are clearly aware of the threat posed by Roberts, the man himself is hoping to give Barnes and new outside-half James O'Connor a hefty welcome in the form of an uncomfortable afternoon's work.
Barnes was one of the standout performers in the Bronze Medal win over Wales at the recent World Cup, while O'Connor stole the show in his first start at No10 in the 60-point hammering of the Barbarians last week.
"Berrick had a terrific play-off game against us. We have made sure this week in defence we are ready to greet James and Berrick as well," said Roberts, who will wear the No12 shirt for Shane Williams' swansong before international retirement.
"We have some big incentives to win. First, it will be Shane Williams' final match for Wales: he has been an inspiration to many and it is frightening to think how many youngsters have taken up rugby through watching him.
"Second, we want to get one back on Australia for beating us in the World Cup last month."