BRIGHTON - The discipline of his team delighted coach Stephen Betham the most on Sunday as Samoa launched their World Cup campaign with a 25-16 Pool B victory over the United States.

"If we can keep 15 people on the park, then we have a chance," he said of Samoa's reputation for consistently losing errant players to the sin bin or having them sent off. "Today was a good start, it gives us something to build on. If we don't keep discipline then we are always in the back foot."

It is an aspect of the Samoan game that Betham says they have worked hard on in their preparations for the tournament, where they next meet South Africa in a match Japan coach Eddie Jones said he expected would be "slug fest". The two countries meet at Villa Park in Birmingham on Saturday.

Despite his delight, Betham said Sunday's win over the Americans had been unconvincing but that there was time to build momentum with four more Pool B games to come and hopes of qualification for the quarter-finals. "We were scrappy but we'll take a win at the end of day and move on from here," he said after the meeting at the Brighton Community Stadium. "We made a lot of breaks but didn't finish it off. There is a lot to talk about before next weekend."