A Japanese kayaker has been banned from competition for eight years for spiking the drink of a rival so that he would fail a doping test.

Yasuhiro Suzuki drugged his key rival at last year's national championships in September. Suzuki spiked the drink of rival Seiji Komatsu with an anabolic steroid, causing him to fail a doping test, the Japan Anti-Doping Agency said Tuesday.

The Japan Canoe Federation began investigating after Komatsu tested positive but denied ever taking drugs. The federation said Komatsu's suspension and records that had been stripped have been restored.

After Komatsu tested positive, Suzuki admitted putting a muscle-building supplement containing the banned steroid methandienone in his drink. Suzuki told the federation that he thought he couldn't win at the national championships, according to Japanese public broadcasting organization NHK.

The incident is Japan's first case of an athlete failing a doping test because of deliberate contamination, according to JADA, which handed down the eight-year ban.

Suzuki and Komatsu had been considered among the top candidates to represent Japan in the 2020 Tokyo Olympics.

The Associated Press contributed to this report.