Marika Koroibete (R) scored two tries in the Rebels crushing win over the Sunwolves. Photo: Julian Smith/EPA

TOKYO The Melbourne Rebels pulverised Japan's Sunwolves 52-7 on Saturday to improve their finals hopes but may have paid a heavy price as half-back Will Genia was knocked out.

Marika Koroibete and Jack Maddocks grabbed two tries apiece as the visitors ran in eight in total, recording their highest-ever score in Super Rugby.

Genia could miss Friday's crunch game against Australian rivals the Waratahs after he was smashed by Amanaki Mafi early in the second half in Tokyo.

A bonus-point victory  their seventh of the season  saw the Rebels improve to 33 points, one behind the Brumbies in the Australian Conference, and climb into the top eight with three regular-season fixtures left.

However, after a promising start to the season, they face a difficult run-in, including games against the Crusaders and Chiefs. 

The struggling Sunwolves, informed by organisers earlier this year that next season will be their last before being kicked out of the southern hemisphere's elite competition, failed to get on the scoreboard in the first half.

The Rebels, who dominated the lineout and scrum, went into the break leading 19-0 before running riot in the second half.

Maddocks scored twice with Dane Haylett-Petty, Michael Ruru and replacement Jordan Uelese also going over to inflict an 11th defeat of the year on the Tokyo-based Sunwolves.

AFP