Leinster's rising star Jonathan Sexton will win only his second cap when he faces the Springboks, reward for his star turn against Fiji on Saturday.

But while the 24-year-old may have dislodged a veteran of 93 caps, O'Driscoll insists Ireland have not yet seen the last of O'Gara.

"The management are looking to give Jonathan an opportunity after he proved himself against an under-strength Fiji side," O'Driscoll said.

"It's another chance for him against the world champions. They're two different prospects.

"Ronan will be disappointed to be sitting on the bench but he's a strong character and has shown time and again that he turns up for the big moments.

"We know he's capable of that and this is just a chance for Jonny to prove his worth."

Ireland's decision to elevate Sexton above O'Gara is born out of necessity rather than any desire to experiment on the behalf of coach Declan Kidney.

O'Gara will be 34 by the time the next World Cup arrives in 2011 and there has been a critical lack of depth at fly-half - until Sexton's arrival.

The Springboks will offer a clearer picture of whether Sexton is the solution and Kidney admitted he needed to see him properly tested.

"I know we have a world-class outside-half in Ronan but we have to find out things about ourselves," he said.

"Jonathan had a good game last week but with respect, Fiji were short of a few so it was difficult to read. I need to find out more.

"I worked with Jonathan last year and gave him the nod for the 'A' team and that answered a lot of questions.

"I know we still have Ronan available. He's disappointed he's not playing buy I can't pick everybody all of the time.

"Ronan is disappointed but is the perfect pro. He's taken it on the chin, has continued training and has contributed to the team exactly as he would normally.

"It was a difficult call but that doesn't really matter. My job is to pick an Ireland team and that's what I've done."