Dallas, Texas (WSAU)The Green Bay Packers are still not sure who will start at one of their outside linebacker spots in Sunday’s Super Bowl against Pittsburgh. Erik Walden, who started the last six games, was limited at practice yesterday with a high ankle sprain suffered in the N-F-C title contest 11 days ago. But rookie Frank Zombo was a full participant in yesterday’s workout, after missing the last six games with a sprained knee ligament. Coach Mike McCarthy said Zombo appears to be back at full speed – and he also practiced with the special teams. The coach said Walden took part in all the drills, mostly with the second team. Meanwhile, Pittsburgh center Maurkice Pouncey missed practice yesterday. He still says there’s a 75-percent chance he’ll play on Sunday. But coach Mike Tomlin says it depends on how he responds to treatments for his high ankle sprain. Also, Steelers’ defensive end Aaron Smith is trying to get ready for the Super Bowl, after being out since late October with a torn triceps. Tomlin says there’s a chance he can play but quote, “it’s fading.” Second-year pro Ziggy Hood has been filling in.