Newcastle wing Alesana Tuilagi will miss the start of the Aviva Premiership season after being hit with a five-week ban.
Samoa back Tuilagi was cited for striking Japan's Harumichi Tatekawa with his knee in the second minute of last Saturday's World Cup Pool B game in Milton Keynes.
In a statement, World Rugby said: "T uilagi denied the act of foul play.
"Having conducted a detailed review of all the available evidence, including all camera angles, medical evidence, evidence from the player and submissions from his legal representatives, the judicial officer Antony Davies upheld the citing on the basis that the player had committed the act of foul play."
Tuilagi's suspension takes effect immediately, ruling him out out of Samoa's World Cup finale against Scotland at Kingston Park on Saturday, plus Newcastle's first four Premiership fixtures against Gloucester, Northampton, Exeter and Worcester.
He is free to play again on November 10.