Zack Bowman said recently he wanted to hear more “oohs” and “aahs” from Nebraska football fans this season as they watched a more exciting Husker defense.

Big Red fans probably released a collective “ugh” Thursday as they learned details of Bowman’s latest injury.

The senior cornerback underwent surgery Thursday to repair a ruptured patellar tendon in his right knee suffered during  practice Wednesday. He is expected to be sidelined for 4½ to six months.

The 6-foot-2, 200-pound Bowman missed all of last season with a torn anterior cruciate ligament in his left knee suffered last August during preseason drills.

“We feel very badly for Zack,” Nebraska head coach Bill Callahan said Thursday in a prepared statement. “He has worked diligently to rehabilitate his previous injury, and this is a tough setback for him. Zack has a tremendous attitude, and I expect that he will work just as hard to get back on the field this fall.”

A native of Anchorage, Alaska, Bowman is regarded as one of Nebraska’s best defenders. He wrestled in January with whether to leave school a year early to enter this year’s NFL Draft. A draft advisory committee projected him as a high second-round choice.

Bowman used his redshirt season last year. If he wanted to sit out this coming season and play at Nebraska in 2008, he would have to petition the NCAA for a sixth year of college eligibility — a rare occurrence.

The top-ranked junior college defensive prospect in the nation by Rivals.com in 2005, Bowman started the final five games of the 2005 season and led the team with 14 pass breakups. He began spring practice last week penciled in as a starter on one side of the field ahead of fellow senior Andre Jones, who started 13 games last season.

At the other cornerback position, senior Cortney Grixby — a full-time starter the past two seasons — entered spring practice listed No. 1 ahead of junior college transfer Armando Murillo, who began classes at NU in January and is practicing this spring.

“It’s the toughest position on a football team to develop,” Callahan has said of the cornerback spot. “You’re putting guys on an island to play man-to-man and to play bump-and-run coverage, where they’re isolated against receivers. And of course, Bowman gave us a big-bodied corner who could match up with the big bodies we see across the Big 12 Conference.”

Bowman’s injury Wednesday occurred as he collided with another player on a crossing route during a 7-on-7 passing drill. He was being held out of full-contact drills this spring as his left knee healed.

If Bowman returns in 4½ months, he would join the team in the midst of preseason training camp in mid-August. Nebraska, coming off a 9-5 record in 2006, opens the 2007 season on Sept. 1 against Nevada at Memorial Stadium.

If Bowman requires six months of recovery, he would return to the team early in October, having missed the first five games, including a Sept. 15 showdown in Lincoln against Southern California as well as the Sept. 29 league opener against Iowa State, also in Lincoln. Nebraska plays in what figures to be a key Big 12 North game Oct. 6 at Missouri.

Nebraska defensive coaches have plenty of options if they feel depth is a problem at cornerback in the wake of Bowman’s latest injury. For instance, senior Tierre Green played cornerback throughout the 2005 season before being moved to safety last season. He is projected as the starter at free safety this season ahead of senior Bryan Wilson, who has also played corner at NU.

In addition, sophomore corner Corey Young drew praise last season for his tenaciouness on special teams. However, he’s sitting out the spring with a shoulder injury.

Also, it’s possible that sophomore Rickey Thenarse and/or redshirt freshman Anthony West — who both moved to safety this spring after playing corner last season — could move back to corner.

Reach Steven M. Sipple at 473-7440 or ssipple@journalstar.com.