But with tougher tests to come against Italy and France in Pool D, the experienced hooker feels Ireland cannot rest on their laurels.
"We're very happy with the result to get the bonus point and the win, it was definitely a lot tougher than the scoreline suggested," said Best, who made 12 starts for Ulster in the GUINNESS PRO12 last season.
"In terms of a start we're very happy with that. There's a few things we've been working on the last couple of weeks since the two losses. A few of those came off, a few of them didn't.
"The warm-up games are always difficult, but we said a couple of weeks ago that we expect to win them, we wanted to win them.
"It didn't go that way but this is the World Cup, we know it comes around every four years and you only get one shot at it.
"It's important that we started well, laid down a marker, but at the same time we're under no illusions that we have to keep getting better every game."
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Guinness PRO12 Ulster News
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