Head coach Vern Cotter has told his Scotland squad to forget about winning their World Cup group for now and instead concentrate on making sure they do not slip up against the United States.

The Dark Blues overcame their first hurdle in Pool B when they crushed Japan's shock troops 45-10 in Gloucester on Wednesday.

Dodging that banana skin just four days after the Brave Blossoms stunned the world with victory over South Africa - and collecting a bonus point with it - was just the start Cotter was looking for.

Scotland have now moved on to Leeds, where they face the US on Sunday, in confident mood having leapt to the top of their section.

But Cotter is refusing to get carried away.

Asked if the Scots were capable of qualifying for the quarter-finals as pool winners, the Kiwi said: "Oh we are getting ahead of ourselves once again. I respect our opponents too much to be predicting anything. We're fully focused on trying to put in a good performance in two days' time.

"We're not on the paddock yet. The game starts on Sunday and we need to be ready for that.

"The players need to be 100 per cent committed and play our best rugby. Then we'll see what happens after that."

With just four days' rest between the first two fixtures, Cotter has announced sweeping changes to his line-up ahead of facing the Eagles.

Henry Pyrgos will lead out the team at Elland Road as he takes over both the captaincy and scrum-half roles from Greig Laidlaw.

With nine other changes, including a first start for Glasgow number eight Josh Strauss, it could be perceived as a gamble against a US side Cotter claims have improved since they were beaten 24-6 by the Scots in Texas last year.

But Cotter believes it is the only way to keep his squad fresh ahead of crucial clashes with South Africa and Samoa later down the line.

He said: "If you have a look at this game, four days after the first and six days before South Africa, it's a pretty tight schedule. So we're adapting.

"It's fair to say it's pretty challenging. We knew what it was going to be though, so we just get on with it.

"It's about energy, it's about those guys coming in that have had less game-time bringing their enthusiasm, redirecting and regenerating those energy levels against a big, powerful team. It is what it is. We'll try our best to get on with it."

The entire bench used against the Brave Blossoms has been promoted to the starting XV.

Pyrgos, who skippered Scotland against Ireland last month, knows this could be his one chance to kick-off a World Cup match, with Laidlaw certain to return for the potentially decisive meeting with the Boks in Newcastle a week on Saturday.

But he intends to make the most of his chance, saying: "It was amazing to lead the team out against Ireland and again it's a huge honour to captain Scotland at a World Cup.

"I know how much it means to the country and I'm really excited. I'm not sure how I'll feel when I get out there but it'll be a big moment for myself and my family.

"Greig had a great game on Wednesday. He kicked a lot of points and was man of the match. But I knew coming in that was how it was going to go.

"I just look at it like it's a great opportunity. I'll focus on my role and do it to the best of my ability. Hopefully we get the right result."

The stand-in skipper will partner stand-off Finn Russell, who retains his place alongside full-back Stuart Hogg, centre Mark Bennett, lock Grant Gilchrist and flanker John Hardie.

Bennett, who scored twice against Japan, will line-up alongside Peter Horne in the midfield, while Tim Visser and Sean Maitland start on the wings.

In the pack Ryan Grant, Fraser Brown and Jon Welsh form the front row, while lock Richie Gray takes over from brother Jonny. Al Strokosch lines up alongside Hardie and Strauss in the loose forwards.

The States suffered a 25-16 defeat in their first match with Samoa but Cotter let a rare smile cross his face when he was asked if they were a sleeping giant.

"I hope they don't wake up for a while," he joked. "I expect them to be very physical, very direct.

"They have speed, size and power. They've been improving. They've worked well to get themselves to the World Cup and recently beat Canada by 40 points. They've also had a week to prepare. They watched us two days ago so they'ill be on the money. But our guys are ready to take that challenge up."