Grzelak spent two years on the Penn State Behrend men's tennis team as the number one-ranked singles and doubles player.
He has a two-time Commonwealth Campus singles champion in 1968 and 1969. In 1969, he was also doubles finalist in the NJCAA nationals. That same year, Grzelak guided the Lions to a second place finish in the NJCAA regional tournament, where he was selected as a first team All-Region player. During Grzelak's career at Penn State Behrend the tennis team lost only one dual match.
Grzelak received the Penn State Behrend Richard Dill Service Award in 1990. Currently, he is Vice president of Marketing for the Kumatsu Dresser Company.