A major question mark loomed when USC opened spring practice last month -- and it had nothing to do with the Trojans' quarterback situation.
The competition to replace Mark Sanchez dominated the buzz before and throughout workouts, but the linebackers trying to fill the shoes of an entire NFL-bound unit also warranted scrutiny.
On Thursday, after USC completed its final practice before Saturday's spring-ending scrimmage at the Coliseum, Trojans coaches expressed delight at the play of middle linebacker Chris Galippo and outside linebackers Malcolm Smith and Michael Morgan.
The trio will replace Rey Maualuga, Brian Cushing and Kaluka Maiava, who along with Clay Matthews gave the Trojans college football's top linebacker corps last season.
Maualuga, Cushing and Matthews are projected as first-round picks in Saturday's NFL draft. Maiava also could be a first-day pick.
Defensive coordinator Rocky Seto does not expect the Trojans to lose a step.
"Believe it or not, these guys are faster in terms of flat-out speed," Seto said.
Seto likened Galippo, a sophomore who has had two back surgeries, to former Trojans All-American Lofa Tatupu.
"He has a great feel for the passing game, directing traffic and is very vocal," Seto said.
Smith, a junior, produced several highlight-reel plays, including a 70-yard fumble return for a touchdown during the Trojans' first scrimmage.
Morgan also played well, though he did not practice Thursday because of a high-ankle sprain that is expected to keep the junior out of the scrimmage.
"We wanted to see what was going to happen with all of the guys leaving and they responded right from the get-go," Coach Pete Carroll said.
The Trojans, however, could have depth issues.
Oft-injured senior Luthur Brown, who can play all three spots, missed nearly all of spring practice because of a shoulder injury. Sophomore Jordan Campbell and senior Nick Garratt played well, but incoming freshmen Jarvis Jones, Frankie Telfort and Marquis Simmons will be expected to contribute.
"They have to play," Carroll said.
Corp's streak ends
Quarterback Aaron Corp finally had a pass intercepted when defensive lineman Jurrell Casey picked off a screen pass.
"I guess it had to happen sometime," said Corp, who had completed 13 workouts without a major error.
The miscue, however, did nothing to dampen the confidence-boost Corp received on Tuesday when Carroll announced the third-year sophomore as the starter for Saturday's scrimmage. The designation will carry through the summer and into training camp.
Corp received about 100 congratulatory text messages from friends, including Sanchez.
"It's just been kind of a crazy couple days," Corp said.
Corp executed one of the most dynamic plays of the spring during a team scrimmage drill late in Thursday's workout. On a third and two, Corp ran a bootleg to the left for a long gain.
None of the quarterbacks who have started under Carroll -- Carson Palmer, Matt Leinart, John David Booty or Sanchez -- could run the way the speedy Corp can.
"You ain't seen many of those with our guys," Carroll said, chuckling. "That wasn't a Booty call, for sure."
Freshman quarterback Matt Barkley responded with a 25-yard touchdown pass on the very next play, showing that despite Carroll's announcement of Corp as the starter, the competition continues.
"This weekend will be somewhat of a response to that announcement for all of the guys," Carroll said. "We'll see how it fits in and how they wear it."
Casey and Christian Tupou are expected to rotate at nose tackle during the season, but Carroll said Casey would be first up. . . . Tailbacks Stafon Johnson and Joe McKnight were absent because they needed to complete academic work, Carroll said. Both are expected to be in uniform for Saturday's scrimmage, though McKnight is not expected to participate as a precaution against re-injuring toes that were dislocated in the Rose Bowl. . . . The Trojans will release their depth chart today, but several positions are expected to be listed with co-starters.