Born in
Hellerup, Piechnik started his senior career with
Kjøbenhavns Boldklub (KB) in the top-flight
Danish 1st Division. He joined
Ikast fS in 1988, and played two seasons for the club. In 1990, he joined
B 1903, and in November 1991 he won his first Danish senior cap. He was part of the
Denmark national team which won the
UEFA Euro 1992. He started the tournament as a substitute, but when
Henrik Andersen suffered an injury in the semi-finals, (ultimately, Andersen would miss the final due to suspension in any event), Piechnik replaced him in the final, for which he earned praise. After the tournament, he followed the majority of the B 1903 players into the merging
FC Copenhagen (FCK) club. Piechnik made 16 first-team league appearances for Liverpool in the
1992–93 season, but only managed one in the whole of the
1993–94 season. When Graeme Souness was replaced by new manager
Roy Evans in January 1994, Piechnik sensed that he was no longer part of the club's plans, and requested a transfer. His lack of success in Liverpool later earned him a selection in the
Liverpool Echo's
Merseyside Lost 11, a selection of players which the newspaper considered the biggest fiascos in the history of Liverpool and
Everton. He transferred to
AGF in Denmark at the end of the season. He won the
1995–96 Danish Cup with AGF, He played the last of his 15 international matches at that tournament, before ending his national team career. He would play on for another three years at AGF, before retiring in 1999. He has worked as both a
real estate agent and
masseur, while still playing "Old Boys" football in Denmark. ==Honours==