Scotland will use the pain of losing second-rower Grant Gilchrist for the rest of the World Cup to drive them on to the knockout stages, according to team-mate Al Dickinson.

The big lock was left devastated after suffering a groin injury in Sunday's 39-16 win over the United States in Leeds which will rule him out of the remainder of England 2015.

It is the latest setback to beset the 25-year-old Edinburgh forward.

He was due to lead out the Dark Blues during last year's autumn Tests but an arm injury suffered on European duty for the Gunners just days after the announcement cost him nine months of action.

Even after returning to fitness, his troubles did not relent. He was again named captain for the warm-up clash with Italy in Turin last month but had to pull out on the morning of the game with a stomach bug.

Now club colleague Dickinson has vowed the team will press ahead towards the quarter-finals in tribute to their fallen comrade.

The loosehead prop told Press Association Sport: "It's a massive blow for us because Gilcho's a leader for us. It's a tough one to take.

"It's really hard because we don't know what to say to him. It's never nice to lose one of your comrades. I know him well with him being my team-mate at Edinburgh so I had a word with him and just told him I was gutted for him.

"He's obviously gutted too but he's a strong character. He's young and will come back. But it's just bad timing. He's had such a bad run. It seems to be one injury after another for him.

"Unfortunately that is rugby. It can be brutal at times but there's not much you can do about it.

"I don't think the negativity of losing Grant will affect us though. We can use his disappointment going forward for inspiration. We'll go out and try to do well for Gilcho. It will fuel us on."

Scotland head coach Vern Cotter is also sweating on the fitness of influential playmaker Finn Russell ahead of Saturday's crucial clash with South Africa in Newcastle, which could play a decisive factor in their chances of escaping Pool B.

The Glasgow fly-half has proven to be the Scots' talisman with his creativity.

But he was spotted at the team's base in Newcastle wearing a protective boot and hobbling about on crutches after coming off against the US with an ankle knock.

Scotland chiefs say his injury will require "further care and assessment" ahead of facing the Springboks but Duncan Weir, who replaced Russell before going on to score the fifth and final try in his first tournament outing, insists he is ready to step up if his rival number 10 fails to recover in time.

He told Press Association Sport: "There's still five days before the game and Finn is a young guy so he will heel quickly but if he doesn't make it I'd certainly hope I would get the chance to step up and face South Africa.

"The World Cup is a special stage and facing the Springboks would be a great honour and one I'd love to grasp with two hands.

"It was tough missing the Japan match. When I got named in the 31-man squad I got a real buzz and I wanted to play every minute. But realistically I knew coming back from injury at the end of last season having not had a lot of rugby that it would be tough to get into the side right away.

"Finn and Peter Horne had both played six months of rugby that I hadn't. So I was patient. I'm a patient young man so I was never going to throw my toys out the pram. I knew I had to stay calm and take my chance when it came along.

"So it was a step in the right direction on Sunday managing to sneak over the whitewash."

The Scots have racked up bonus-point victories over Japan and the Americans on their way to topping their group after two games.

However, all 10 of their tries have come in the second half following sluggish starts.

Weir admits the Scots will not get away with that against the Boks.

"South Africa are going to come out all guns blazing," he said. "They know they need to get a game back on the one that they lost so it will be a huge opening 20 minutes.

"They use their physicality well and we need to match them. Credit to them, they play to their strengths. But when you wear the Thistle you realise that we have our own strengths and it's about using them to cause our opponents problems."