As the United States prepared to face Japan in the knockout stage at the Tokyo Olympics in 2021, Nick Martinez issued a warning to his peers.

¡°Don¡¯t swing at the fork,¡± Martinez, now a star relief pitcher for the San Diego Padres, told them. Martinez was referring to Kodai Senga of Japan and his forkball, which is nicknamed the ¡°ghost fork.¡±

Martinez had spent four seasons in Nippon Professional Baseball in Japan, as both a teammate and an opponent of Senga¡¯s. He knew how haunting the ghost fork could be, yet his fellow Americans could not lay off the pitch.