Kollar began his NFL coaching career as the defensive line coach for the Atlanta Falcons in 1990. He spent more than a decade (1990-2000) coaching the defensive line for the Falcons, highlighted by an NFC Championship in 1998 and an appearance in Super Bowl XXXIII against Denver. Kollar then spent five seasons coaching the defensive line in St. Louis. Kollar’s defensive line was instrumental in the Rams’ 2001 Super Bowl run as the club ranked third in the NFL in rush defense (85.9 ypg) while tying for the seventh-most sacks (45) in the league. Kollar then spent three years coaching the defensive line in Buffalo (2006-08), where he coached future All-Pro defensive tackle Kyle Williams and two-time Pro Bowl defensive end Aaron Schobel.