Yamaha test rider Kohta Nozane will make a surprise MotoGP debut at this weekend's Japanese MotoGP after being parachuted into the Monster Yamaha Tech 3 team in place of Jonas Folger.

Folger returned to Germany for medical tests after struggling with severe fatigue, prompting fears he has a recurrence of the Epstein Barr virus.

But Tech 3 will still have two bikes on the grid at Motegi this weekend after offering 21-year-old Nozane the last-minute chance to make his premier-class debut.

"This is big surprise for me! I still can’t believe that I will ride at the Grand Prix of Japan," he said. "Motegi is my favourite circuit, and I have ridden the YZR-M1 with Michelin tyres here before as a Yamaha test rider. It will be an honour to ride on home soil like a MotoGP rider. I would like to thank Yamaha and Monster Yamaha Tech3 for giving me this opportunity."

Team manager Herve Poncharal added: “After the very sad and disappointing news that Jonas Folger can not take part in the Japanese Grand Prix, I am pleased to say that the #94 side of the garage will be racing this weekend. We are proud to announce that Kohta Nozane will compete for us here. He is a really important rider for Yamaha Motor Company and has raced in many different championships, including the World Endurance Championship.

"When we knew that Jonas was going to have to withdraw from this GP, we talked with Yamaha and it made perfect sense to choose Nozane. He knows Motegi quite well and I think he won a race here this year in the Japanese Superbike Championship. He tested the M1 in January, which will clearly be a big help for him to show what he can do. We don’t expect too much because this is one shot and he doesn’t have MotoGP experience.

"However, one thing that will be interesting is his mentor, Nakasuga, who is a wildcard on another YZR-M1 and I’m sure they will be happy to compete against each other. We are pleased to have found the possibility for two riders to race for Tech3 this weekend. We don’t want to put any pressure on Nozane, but we just want to thank him, YMC, Mr Tsuji and Mr Tsuya, who have helped us tremendously to have this opportunity.

"We hope that we can give Nozane a good experience, which will help him grow as a racer and hopefully as a MotoGP rider in the near future. Let's see what happens, but the weather forecast does not look so good as there will certainly be sure rain during the weekend. Nevertheless, I want to say thanks and welcome him to our team.”

Nozane has made four previous grand prix starts, all in Moto2, back in 2012 and 2013, without scoring points. As well as Yamaha test riding duties, Nozane has raced in the Japanese Superbike Championship and World Endurance.

Folger is also in doubt for the following Phillip Island and Sepang rounds, depending on the medical tests.