Andrew Quarless knows the exact pattern former tight end Isaac Smolko ran on fourth-and-15 the last time Penn State played at Northwestern.

Streak down the middle of the field and make a slight move inside, nestle inside the zone coverage.

Four years later, the play is still in the playbook, but quarterback Daryll Clark may not get a chance to find Quarless like Michael Robinson found Smolko because Quarless is starting to grab the attention of opposing coaches with his ability to stretch defenses in the vertical passing game.

Last week at Michigan, the Wolverines' safety was more concerned with stopping wide receiver Derek Moye on the flank, and Quarless was able to blow by linebacker Obi Ezeh for a 60-yard touchdown catch, his first score in the last 16 games.

Four days a week in practice, Penn State safety Nick Sukay faces the same dilemma of deciding who to help cover.

"It all depends what coverage you're in," Sukay said. "Each week you'll watch them on the field. I really don't know who I'd worry to help with. That's the problem if you're in the secondary."

Saturday, balancing Quarless and the wide receivers tops the list for Northwestern -- once it figures out who can play.

Wildcats coach Pat Fitzgerald is confident safety Brad Phillips will be able to play through a lingering shoulder injury. Also, the status of safety Brendan Smith is unknown. He is recovering from thumb surgery.

Cornerback Sherrick McManis has dealt with ankle and quad injuries for much of the season and probably won't be at full strength.

Northwestern's safeties like to stick their noses in and stop the run, Clark said, meaning play-action passes may be popular Saturday.

Quarless rarely is a target if the linebacker has safety help over the top. But Clark said his tight end has done a better job at getting open, making defenders react to where he is on the field.

Once the ball is in Quarless' hands, it presents another challenge. Clark said the size -- 6-foot-5, 248 pounds -- of his tight end makes him tough to bring down. And, Clark feels his ability to gain separation goes unnoticed, making him a favorable target whenever he has one-on-one coverage.

"Defenses scout me and know my speed, so we don't get it as much as I would like," Quarless said. "But it's like I've told Daryll, 'Show me a receiver that doesn't want the ball, and I'll show you a receiver that's not good.' "