Three months into the new year, former UFC champions Demetrious Johnson and Eddie Alvarez will make their ONE Championship debuts.

Johnson (27-3-1), the UFC’s inaugural and long-reigning flyweight titleholder, will fight Yuya Wakamatsu (10-3) in a flyweight bout. Alvarez (29-6), who was a lightweight champion for the UFC and Bellator, will take on Timofey Nastyukhin (12-4) in his debut with the promotion. ONE Championship today revealed the bookings to The Associated Press.

ONE Championship will make its debut in Japan on March 31 at Ryogoku Kokugikan, an 11,000-capacity venue near Tokyo. The event is expected to stream on ONE’s app.

The promotion previously announced the Johnson and Alvarez debuts will be part of flyweight and lightweight grand prix tournaments, though at the time their opponents were not yet known.

Also on the card, atomweight champion Angela Lee will move up to challenge strawweight champion Xiong Jing Nan, and middleweight champ Aung La N Sang and lightweight champ Eduard Folayang will defend their belts. Sang will take on Ken Hasegawa in a rematch of what many consider the promotion’s best fight to date, while Folayang will meet former champion Shinya Aoki in another rematch.

Johnson was part of an historic “trade” between the UFC and ONE Championship that saw former ONE welterweight titleholder Ben Askren freed from his contract to join the UFC, nearly a year after he retired, and Johnson freed from his UFC deal to sign with ONE. Alvarez fought out his UFC contract and signed with ONE as a free agent.

Johnson won the UFC’s flyweight title in 2012 and held it till earlier this year, when he lost a split decision to Henry Cejudo in a rematch. He set the UFC’s record for consecutive title defenses before the upset loss to Cejudo.

Alvarez won the UFC’s lightweight title in 2016 against Rafael dos Anjos, but lost it four months later in his first defense against Conor McGregor.

For more on ONE Championship in Japan, check out the MMA Rumors section of the site.