Texans audition for backup at safety;With Manning hurt and Nolan promoted, opportunity knocks for

Week 8 Texans vs. Jaguars Noon Sunday at Reliant Stadium TV/radio: CBS; 610 AM, 100.3 FM, 1010 AM (Spanish). ... Chat with the General Join John McClain in our weekly chat at 11:30 a.m. today online and via the Chronicle's iPad app. chron.com/iPad, chron.com/sports The Texans did not place free safety Danieal Manning on injured reserve Monday because they believe he might return this season. After undergoing surgery Monday morning to repair a fractured fibula in his left leg, Manning, 29, will begin rehabilitation immediately. Still, there's no guarantee Manning will return this season. Manning (5-11, 209) was injured while making an interception in Sunday's 41-7 victory at Tennessee that catapulted the Texans (4-3) into first place in the AFC South. "We think there's an opportunity for him to come back this year," coach Gary Kubiak said. "Time-wise, I can't give you an answer right now, but we're definitely talking about somewhere (between) four weeks and beyond, whatever that's going to be." Manning, who received $9 million guaranteed to sign with the Texans in the offseason, was playing well. He had become the leader of the secondary. "We'd love to get him back before this season's over," Kubiak said. "We'll see how the progression goes over the next three weeks and see if that's going to be a possibility, but right now we think it is." Troy Nolan, 25, who's playing in his third year, replaced Manning against the Titans and will replace him in the starting lineup. "Troy played very well, and he has been playing well," Kubiak said. "He's always had a knack for the ball. When he's played, he's come up with interceptions and come up with big plays. "The thing for Troy will be getting comfortable with the mental part of the game to where it's easy for him and his talents take over. That's been something that we've been looking for. "He played more than 30 snaps (at Tennessee) without any mistakes, and that's a very positive sign. I just think they (defensive coordinator Wade Phillips and secondary coach Vance Joseph) have done a good job with him." With Nolan (6-2, 202) joining strong safety Glover Quin in the starting lineup, there will be competition for the backup job. Beaten for TD Rookie Shiloh Keo, a fifth-round pick, was promoted from the practice squad last week to replace the injured Dominique Barber (foot). Keo (6-0, 212) played against the Titans and was called for a personal foul penalty and was beaten on Tennessee's only touchdown. Rookie Brandon Harris (5-10, 195), a second-round pick, is moving from cornerback to safety to compete for the backup job. Torri Williams, a safety on the practice squad, also is a possibility. "We have options," Kubiak said. "Keo played a lot. Torri has the ability to possibly come up, but right now, we really like what we see from Brandon Harris. He's a smart player. We think he can go play some safety." Positives for Harris Fans have been wondering when Harris was going to contribute, considering how high he was drafted. "We've been crowded at corner, so that's made it tough on him," Kubiak said about Harris not getting more playing time. "He hasn't done anything wrong. He's done some good things. "He's a bright player, understands schemes and understands what's going on. "We think Wade and Vance can catch him up real quick. We're going to take a look and give him an opportunity and work with him over the course of this week. "We're going to see how things go this week, watch those guys work, and decide where we move from there. We'll see who can handle it the best." john.mcclain@chron.com twitter.com/mcclain_on_nfl ... OPEN AUDITIONS With Danieal Manning out, the Texans will look to these players to fill the void at free safety: Troy Nolan Experience: 3nd year College: Arizona State 2011 stats: 17 tackles, 0.5 sacks, 3 passes defended Shiloh Keo Experience: Rookie College: Idaho 2011 stats: 1 tackle Brandon Harris Experience: Rookie College: Miami 2011 stats: 1 tackle