Buuxi weedha soo socota: Koivisto wuxuu ka soo jeedaa Ylitornio, Finland, wuxuu u guuray Rauma isagoo dhalinyaro ah 1998 si uu ugu ciyaaro Lukko, maadaama waqooyiga Finland aysan laheyn koox SM-liiga ah waqtigaas. Kadib hal sano oo uu la qaatay kooxda Lukko junior A, Koivisto wuxuu ku soo biiray SM-liiga xilli ciyaareedkii 1999-2000, in kasta oo uu wali u qaybiyay waqtigiisa kooxaha qaangaarka iyo kuwa yaryar. Sanadkii 2000, Koivisto wuxuu ka soo muuqday U18 World Championships wuxuuna ku guuleystay billad dahab ah Kooxda Finland. Waxa kale oo uu Finland ku matalay Golaha Wakiillada.
2001 iyo 2002 World Junior Championships, oo gurigooda ku soo laabtay lacag iyo naxaas, siday u kala horreeyaan.