Grening started his career with FC Roskilde’s youth academy and played for the first team between 20219 and 2021. Here he represented the club in both the NordicBet League and the 2nd Division. During his time at FC Roskilde, Grening made 15 appearances in the NordicBet League, as well as 10 appearances and three goals in the 2nd Division. He spent the 2024 season at the University of Pittsburgh, where he helped the Pittsburgh Panthers become part of the prestigious ‘Elite Eight of the U.S. NCAA College Cup’. Grening contributed six goals and four assists in 20 games. He previously played three seasons at the University of Kentucky, where he scored 11 goals and made six assists in 41 games.