Japan scrum-half Fumiaki Tanaka has admitted lobbying for his side's second-half penalties to be kicked to the corner, but was overruled by captain Michael Leitch as he looked to tie up victory.

The Brave Blossom delighted another record Stadium MK crowd with a whirlwind first-half performance that saw them build a 20-point lead.

However, there were playful boos from the majority in attendance in the 59th minute as man of the match Ayumu Goromura kicked a penalty through the posts rather than into the Samoan 22.

Akihito Yamada scores Japan's second try© Michael Steele/Getty Images

Tanaka revealed the plan had been to go for the jugular in the final quarter of the half but the late try blitz never materialised and with South Africa winning in Newcastle, Japan's failure to gain a bonus point could well prove damaging.

"I talked to Leitch, I wanted to go for touch as we needed a try," Tanaka said.

"But Leitch said shot [at goal] and then in the last 10 minutes we'd push the tempo up and [go for] the try. So, I wanted a line-out but his opinion was win first."

Japan lock Luke Thompson conceded that his side's inability to turn pressure into points could cost them a quarterfinal place but insisted he would back his captain "any day of the week".

After all it was Leitch's decision that gave the World Cup one of its biggest shocks when they shunned three points to score a match-winning try against the Springboks.

"I'd back Leitchy any day of the week. He's making great calls and we had to win the game," he said. "We had to make sure it was secure and there was time to score bonus points.

"But Samoa are a [dangerous] side, as you saw they scored a length of the field try, couple of turnovers and they're back in it, a three or four point game and you're under the pump."

And he believes there is more to come from the Brave Blossom. "It was a good performance, to win any game in the World Cup is really great achievement," he added.

"I didn't think we played our best though, we played a lot of good things and it was a really gutsy effort but we left a few tries out there and that could cost us later on. But we won a World Cup game and that's special so we've got to savour that."