Panasonic Wild Knights maintained their unbeaten run in the Japan Rugby Top League with a 41-12 victory over Honda Heat on Saturday at Nishikyogoku Athletic Stadium.

Veteran scrumhalf Fumiaki Tanaka was at the heart of the Panasonic effort, forcing a number of turnovers and dictating the pace of the game in wet slippery conditions, as Robbie Deans' side ran in seven tries to all but wrap up their spot in the playoffs.

However, they will have to wait at least another day, and possibly another week, to mathematically confirm their place after Kubota Spears upset Ricoh Blacks Rams 22-16.

Panasonic head the White Conference with 22 points, three more than Yamaha Jubilo, who beat Toshiba Brave Lupus 27-7.

Ricoh are third on 15 points, Kubota a point behind in fourth and Toshiba fifth on 11 points.

If Canon Eagles (sixth with 7 points) fail to record a bonus-point win on Sunday against bottom side Coca-Cola Red Sparks, then Panasonic will secure their place with two weeks to spare.

This season, the league's 16 teams have been split into two Conferences -- Red and White. Following seven rounds of pool games the top four sides from each group will play for the league title.

The bottom eight sides will fight it out to determine which four will enter relegation/promotion playoffs with the top four teams from the second-division Top Challenge League.

In the day's only game in the Red group, Toyota Verblitz hammered bottom side Munakata Sanix Blues 52-7 to leave Jake White's side top ahead of Sunday's four league games.

Verblitz have 18 points, Kobe Kobelco Steelers have 15, with Suntory Sungoliath, Toyota Industries Shuttles and NTT Communications Shining Arcs all on 12.

Played in heavy, and at times torrential, rain, the Wild Knights got out to a 19-0 lead inside 21 minutes thanks to tries by Daniel Heenan, Harold Vorster and Atsushi Sakate, the first and third of which came from well-constructed rolling mauls.

However, Honda hit back with Lomano Lava Lemeki first creating a try for Nobutaka Ubukata before scoring a superb individual effort himself to make it 19-12 at the break.

Sakate, who was leading Panasonic for the first time, added a second early in the second half from yet another line-out close to the Honda line, before man-of-the-match Vorster also made it a brace with a weaving run in the 56th minute.

Further tries came from Ryuji Noguchi and Yuji Shimogama with Takuya Yamasawa ending the day with three conversions.