Scotland coach Vern Cotter has admitted there were nerves inside the camp before their opening Rugby World Cup fixture against Japan.

Cotter, who eventually watched his side overwhelm Japan 45-10 at the Kingsholm Stadium, admitted he was worried following Japan's famous win over South Africa on Saturday.

"Watching everyone else play has been a little nerve wracking, especially when we saw Japan's performance against South Africa," said Cotter after only Scotland's third victory in their last 10 internationals.

"We've been watching them [Japan] for two and half months and weren't surprised by their tenacity, motivation and commitment against the Springboks. They've had this World Cup in mind for a long time and it showed today.

"But we're happy to get the win, happy to pull away in the second half and happy to get started."

Cotter's concerns have now switched to the limited amount of rest time between now and their next fixture against the USA on Sunday in Leeds.

"At the moment I think there's a few stitches to go in, which means we're committing ourselves, so that's a good sign," added Cotter. "The four-day turnaround will be difficult, and to be fair I think Japan found that hard today. We'll be focusing on our recovery."

Cotter's side looked like they could fall the same way as the Springboks during the first half as Amanaki Mafa carried over the opening try for the Brave Blossoms. But Scotland soon got their act together in the second half, running home five tries aided by a Mark Bennett double, ensuring their win also brought a bonus point.

Captain Greig Laidlaw, who kicked 20 points, was relieved to have finally got the campaign underway

"It was nervous to sit back and watch everyone else play," Laidlaw admitted. "There was no place in our performance for complacency, and I think you saw that today in our performance.

"Vern told us not to panic at half-time. This is the fittest Scottish team in a long, long time and you've seen that in the warm-up games and again today. We're in a good place, fitness-wise."