Mezue ahịrịokwu na-esonụ: N'etiti ọrụ afọ anọ ya na TPS na junior SM-liiga, ndị Flyers họpụtara Niittymäki na 168th n'ozuzu na
1998 NHL Entry Draft. Ọ gara n'ihu na-egwu na Finland na TPS maka afọ mbụ ya site na obere egwuregwu, ma ọ meriri iko Rookie nke Afọ nke Finnish elite league. Mgbe oge abụọ ọzọ na TPS gasịrị, Niittymäki kwagara North America iji sonyere Philadelphia Phantoms na American Hockey League (AHL). Mgbe ndị Phantoms meriri asọmpi AHL Calder Cup, akpọrọ ya MVP nke egwuregwu playoffs. Mgbe ahụ, ọ na-egwuri egwu oge anọ maka Philadelphia Flyers tupu ya abịanye aka dị ka onye nweere onwe ya na Tampa Bay Lightning. Otu afọ mgbe e mesịrị, ọ bịanyere aka na San Jose Sharks dị ka onye nweere onwe ya, mana ọ naghị egwu ọtụtụ egwuregwu maka ha n'ime afọ abụọ sochirinụ n'ihi mmerụ ahụ hip. Ọ gbara oge ikpeazụ ya na ndị otu ntorobịa ya TPS, wee kwupụta ezumike nka ya na 2013.