Scotland must keep their foot to the floor in the search of more bonus points as they prepare to face USA at the Rugby World Cup, says former wing Tony Stanger.

An opening 45-10 thumping of Japan brought Eddie Jones' men back down to earth after their stunning win over South Africa, as well as leaving Scotland well-placed to get out of Pool B.

Five second-half tries were the highlight of an impressive performance from Scotland in Gloucester, and Stanger is hoping they will also put tournament outsiders to the sword at Elland Road on Sunday, with the Springboks to follow next weekend.

"I was very impressed," Stanger told Omnisport after Scotland's win over Japan.

"The main thing for me was some of the things that we did are things that we've been struggling with in the past, particularly scoring tries when we have a half break. 

"So to get the five tries was excellent. We managed to take our chances against a good team which bodes well for the next game, USA are going to be tough and then we've got two really big games after that."

He added: "It really is important [to get another bonus point], we thought it might've been a three-horse race [in the pool] but that Japan result against South Africa really put the cat amongst the pigeons and bonus points will be crucial. 

"It is probably a good thing – of the three games left – this is sort of the 'easier' one, although the downside is it's not far away. We have not got a lot of recovery time but everyone probably has to go through that at one point, so it is probably not a bad time to go through it. 

"A win would be a good thing, nine points out of 10 would be a good result, and then maybe see how South Africa go against Samoa. I think it [beating USA] is crucial. 

"Outcomes and results are crucial, but the quality of the performance is what we'll be most confident from and I think they can take that into to the match with USA, and you'd be disappointed now if we weren't close to getting a bonus point."