Posted by ESPN.com's Tim Griffin

It's not unprecedented that Oklahoma could come back from a loss to Texas and still win the Big 12 South title and maybe a factor in the national title chase.

But it's going to be very hard.

The Sooners are left with this predicament after suffering a 45-35 loss to the Longhorns last week, twice blowing double-digit leads against their resilient archrivals who are now in the driver's seat for the South Division title.

If Oklahoma coach Bob Stoops has any legitimate shot at earning a three-peat of Big 12 titles, he'll need to fix several nagging concerns quickly as the Sooners head into Saturday's pivotal game in Norman against North Division leader Kansas.

The Sooners' biggest concern is replacing playmaking middle linebacker Ryan Reynolds, who was lost for the season after blowing out his right knee early in the third quarter last Saturday.

After Reynolds' departure, the Longhorns took over running the ball, producing 164 rushing yards in the second half. Texas was limited to minus-3 yards rushing in the first half.

Before Reynolds' injury, the Longhorns produced 4.6 yards per snap. After he left the lineup, Texas gashed the Sooners for 8.3 yards per play and outscored the Sooners 25-7 to claim the comeback victory.

Brandon Crow struggled as Reynolds' replacement in the Texas game against both the run and the pass. It is unlikely he'll get the chance to start against Kansas.

Stoops mentioned starting weakside linebacker Travis Lewis as a possible replacement in the middle, but after the redshirt freshman produced 19 tackles against Texas, it is unlikely that he would move. A more plausible solution would be moving his backup, redshirt freshman Austin Box, or junior-college transfers J.R. Bryant and Mike Balogun.

The hole is the middle is present because 2007 Big 12 Defensive Player of the Year Curtis Lofton left school a year early to declare for the NFL Draft. And heralded 2007 junior-college prospect Mike Reed left school earlier this year, robbing the position of additional depth.

"These other guys are going to have to step up," Stoops said.

Another huge concern has been the Sooners' struggles covering kicks. The Sooners rank 109th nationally, allowing an average of 25.33 yards per kick. They've been burned for touchdowns by Mardy Gilyard of Cincinnati and Jordan Shipley of Texas and nearly gave up a touchdown to Aaron Brown of TCU.

The memory of Shipley's return still stings because it enabled the Longhorns to stay in the game when it appeared the Sooners were on the verge of a knockout after going ahead 14-3 early in the game.

"We just haven't been able to get it done," Stoops said.

The Sooners also rank ninth or worse in the Big 12 in punt return average and net punting. It's a very rare problem for a Stoops-coached team to have.

The Oklahoma coach was a pioneer among modern coaches of putting starting players on his special teams. Key contributors like Teddy Lehman, Rocky Calmus, Roy Williams and Trent Smith all had their time on those special-teams units.

But the Sooners have gotten away from that in recent years. Stoops hinted earlier this week that that attitude could change after playing only four starters on the kick coverage unit last week against Texas.

"We aren't doing anything differently, it's just people," Stoops said. "We have got to get the right guys in there who can recognize and be where they need to be. Sometimes, we've been where we needed to be and we just didn't make the play."

The Sooners also need to be more balanced offensively after struggling to run the ball against both Texas and TCU in their last three games. Oklahoma produced 48 yards against the Longhorns after netting 25 against TCU.

"We know that it hasn't been as good as it has been since the beginning of the season," Oklahoma tailback Chris Brown said. "We have to take responsibility for what is going on in the running game. It's not just the offensive line. It's the backs and the complete offense. This is a week where we have to establish our running game and get it back like normal."

Tailback DeMarco Murray is clearly not the same back he was last season before dislocating his kneecap in a late-season loss at Texas Tech. Murray has had only one gain of more than 20 yards this season and is averaging 4.8 yards per carry this season after averaging 6.0 yards last season.

"We need to be a better run team because we're not trying to be a finesse team," Oklahoma offensive coordinator Kevin Wilson said. "If the run game is not going, I have to make it work and give us a chance to win."

Those adjustments will be critical for the Sooners to make immediately. Their Big 12 title hopes will be riding on them.

But the Sooners like their place in the national title hunt midway through the season -- even after the loss to Texas.

"There's still a lot of football left," Lewis said. "There's a lot of football still to be played."