Glen was accused of lacking a good attitude toward his game by manager Csaba László and consequently failed to become a regular in the Hearts team during season 2008–09. He failed to make another first team appearance until 27 December 2008, appearing against Aberdeen as a substitute. On 11 January 2009, Glen came off the bench with 10 minutes remaining and scored a decisive 94th-minute goal against Hibernian at Easter Road in the fourth round of the Scottish Cup to knock Hearts' city rivals out of the cup.