Ayumu Goromaru scored 16 points to keep Japan in the race for a historic appearance in the Rugby World Cup quarter-finals as they beat Samoa 26-5 on Saturday.
The 29-year-old, who starred in the epic win over South Africa two weeks ago, became the leading tournament points scorer with 45.
Japan also scored two tries, a penalty try and one from wing Akihito Yamada.
Samoa paid for their lack of discipline losing three players to the sin bin in the game.
The win at Milton Keynes takes the Japanese – who before this World Cup had won just one match and that back in 1991 – onto eight points ahead of their final game with United States next weekend.
Goromaru looked to have given Japan a dream start as he went over in the left hand corner but linesman Wayne Barnes signalled for a forward pass leaving coach Eddie Jones fuming.
South Africa referee Craig Joubert, who had been playing an advantage anyway, awarded the Japanese a penalty instead and Goromaru shrugged off the disappointment to slot over the penalty.
Samoa were reduced to 14 men for 10 minutes when No.8 Failfili Levave was sin-binned for making no attempt to tackle hooker Shota Horie, simply bending his shoulder into the Japanese player and sending him flying.
Joubert read the riot act to Samoan captain Ofisa Treviranus about conceding penalties and the South African wielded another yellow card when prop Sakaria Taulafo took out a Japanese player in the air – leaving the Samoans with just 13 men on the pitch.
The Pacific islanders defended stoically as the Japanese pounded away at them.
The Asian champions eventually came away with a penalty try which Goromaru converted for 10-0 after 24 minutes.
Goromaru added another three points as a result of a Samoan going offside to make it 13-0 against a ragged opponent who were in danger of being out of the game by half-time.
Indeed they were as Akihito Yamada did a good impression of a spinning top completely fooling Alesana Tuilagi and went in in the far right hand corner after good work by the pack for his fifth try in five Tests this year.
Goromaru – whose points tally took him past South African Morne Steyn on the all-time Test scorers – made the half-time cup of tea taste even sweeter as he converted brilliantly from the touchline for 20-0.
The Japanese fullback added another three points to make it 23-0 early in the second-half
Japan skipper Michael Leitch pulled off a try-saving tackle seconds later, as Samoa finally put together an incisive move, bringing down halfback Kahn Fotuali’i.
Yamada’s day ended prematurely as his brave effort at tackling Paul Perez ended with him knocked out on the pitch.
It did not distract the Japanese from their game plan with Goromaru converting another penalty for 26-0.
Finally, though, the Samoans put a thrilling and fluent passing move together ending in Perez going over in the far left hand corner.
Tusi Pisi’s conversion hit the post to leave Japan leading 26-5 and the Brave Blossoms comfortably saw out the rest of the game for another superb win.