Weir handed key role against Boks

Newcastle - Duncan Weir will have the heavy responsibility of directing play for Scotland in their crucial World Cup match with South Africa on Saturday.

The 24-year-old has been named at flyhalf because first choice Finn Russell has not recovered from a knock to his ankle suffered in the 39-16 win over the United States last Sunday.

"I've been waiting on my chance and as soon as the squad for Saturday got announced I had to pinch myself - I'm going into St James' Park to start at a World Cup," said Weir.

"I wouldn't say I feel pressure with what's at stake on Saturday - more excitement. We're one win away from a quarter-final with two games left."

Russell's absence is a major blow to the unbeaten Scots. He played a key role in the wins over Japan -- scoring a try on his 23rd birthday -- and United States which saw them collect maximum points.

Hordes of tartan-clad and kilted Scottish fans -- though deprived of their bagpipes inside the stadium -- are expected to pour over the border to witness their side's standout Pool B match in Newcastle.

Weir, though, is not worried about being thrust into the limelight despite only having played 20 minutes of the tournament so far.

"I think about what I can bring as an individual. I think about what I can control. There's no point me thinking about outside factors like that.

"For me, it's about doing my job really well, making sure I boss the team and (am) really vocal in attack. Those things are all in my control and I'll just focus on that.

Scotland top the table by three points from the Springboks, who bounced back from losing 34-32 to Japan by hammering Samoa 46-6 last Saturday.

Coach Vern Cotter, who has already lost influential lock Grant Gilchrist for the rest of the World Cup, has made 10 changes from the side that beat United States to take on the Springboks.

Gilchrist's place in the second row goes to veteran Richie Gray, who will win his 50th cap, and partners younger brother Jonny in the engine room of the scrum.

Cotter has also thrown New Zealand-born flanker Blair Cowan straight into the starting line-up as another Kiw-born back row forward John Hardie sits a second straight game out after suffering a head injury in the win over Japan.

Elsewhere Cotter has preferred Netherlands-born wing Tim Visser, who scored a try against the United States, to veteran Sean Lamont, who started the Japan game but is on the bench for this Test.

Cotter, who has transformed the Scots from a motley disillusioned squad into an attractive rugby playing side since he arrived in May 2014, refuted suggestions he was surrendering the game in favour of picking his first team for the game with Samoa on October 10.

Depending on Saturday's pool results it could be a winner takes all match in terms of who makes the quarter-finals.

"This is our third game in 10 days," said the 53-year-old New Zealander.

"These players will be giving 100 percent of themselves and it is a team that will be competitive."