Defending champions Saitama Wild Knights held off Toyota Verblitz 19-10 on Saturday to clinch a Japan Rugby League One playoff berth with their 13th straight win of the season.

Both teams struggled with the slippery ball at a rain-soaked Toyota Stadium, but the visitors gave away fewer penalties and punished their opponents' mistakes to remain the top division's only undefeated side.

Rikiya Matsuda slotted a pair of penalties before Lood de Jager's converted try put Wild Knights 13-0 up.

Saitama Wild Knights' Shota Fukui (front) is tackled by Kazuki Himeno of Toyota Verblitz in a Japan Rugby League One match on March 25, 2023, at Toyota Stadium in Toyota, Aichi Prefecture. (Kyodo)

Yoshikatsu Hikosaka crossed after the 40-minute mark for Toyota, with Tiaan Falcon adding the extras to make it 13-7 at halftime.

The teams traded three-pointers before Japan playmaker Matsuda completed the scoring with a 75th-minute penalty for Wild Knights, who crossed late with a rolling maul but were held up in goal.

Having racked up 58 points with three rounds of the regular season remaining, coach Robbie Deans' Wild Knights are now guaranteed a top-four finish.

In Saturday's other first-division match, Yokohama Eagles wing Burua Inoke scored a hat trick of tries in a 64-12 victory over winless Hanazono Liners.

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