[1] Sačer started playing football at 6 years of age for his hometown club Drava Sveti Đurđ, moving soon to Podravina in nearby Ludbreg and finally joining the youth ranks of Varteks in 2000.
He came into the spotlight playing for the Varteks U-19 team, when he was named the best player and scorer of the Prva HNL Academy for the 2008–2009 season, amassing an impressive tally of 32 goals and 14 assists in 30 games, 11 goals more than the runners-up Andrej Kramarić and Valentino Stepčić.
He made his first team debut for Varteks in May 2009, entering for the last 8 minutes in the game versus Osijek.
He joined the ranks of Hajduk Split, of which he stated to be an avid fan, in late June 2009.
He remained on loan with his hometown club, which had changed its name from NK Varteks to NK Varaždin, for the first half of the 2010–11 season, finding his position moved more and more moved to the right wing, and unable to regain his scoring streak.