"Results back nothing serious, small tear so hopefully still be able to (box)," Williams said on his Twitter page after the scan.
A serious injury for Williams would have thrown his fight against South African Francois Botha in Brisbane next month in doubt.
The 27-year-old, who scored a first-minute try in Panasonic's 23-20 win over Kintetsu Liners, was taken to hospital after the match with his right arm in a sling.
Williams left the world champion All Blacks and Waikato Chiefs for a 12-match deal in Japan worth an estimated $100,000 a game.
Panasonic have yet to see a bumper return on their investment, with the Wild Knights fifth in Japan's Top League standings, 14 points behind leaders Suntory Sungoliath.
Last year's runners-up Panasonic have yet to click and an injury would pile more pressure on Williams, who has already admitted to feeling the weight of his huge price tag.
Defending champions Suntory continue to make it look easy, however, thrashing Fukuoka Sanix Blues 42-19 to make it eight wins from eight.
Record holder Hirotoki Onozawa's 100th Top League try ensured that Suntory go into the month-long winter break four points clear at the top with 39 points from a possible 40.
