As head coach Muižnieks has led his teams to multiple championships, winning titles in domestic and international competitions.
First success in European club tournaments Muižnieks had with BK Ventspils, where in 2002/2003 his squad he finished third in FIBA Europe Champions Cup, where in bronze medal game they upset KK Hemofarm and their up-and-coming star Darko Milicic.
[2][3] Under coach Muižnieks Trefl Sopot won Polish Cup and for the first time made league finals, where they lost only in Game 7 to Asseco Prokom.
Success under Muižnieks in Polish league clinched EuroCup berth for Trefl Sopot.
Muižnieks' squad had a strong season as Khimik made Eurocup quarterfinals for the first time in club history and reached finals of Ukrainian League.