Liufau (forearm) was placed on injured reserve by the Cowboys on Sunday with a designation to return, Nick Eatman of the team's official website reports.
Liufau suffered a broken left forearm during the team's preseason finale against New Orleans on Friday. The linebacker will now be forced to miss at least four contests to open the regular season while on IR. Liufau is primarily a special-teams asset, so his absence won't carry a major impact on defense.