Updated

TCU quarterback Casey Pachall is expected to be sidelined around eight weeks after fracturing his left forearm in Saturday's win over Southeastern Louisiana, according to the Fort Worth Star- Telegram.

The senior underwent surgery on his non-throwing arm following the No. 24 Horned Frogs' 38-17 victory, a source told the Star-Telegram, which will likely keep Pachall out until early November at the earliest.

Pachall started all 13 games as a sophomore for TCU in 2011 and led the Horned Frogs to an 11-2 record and a win in the Poinsettia Bowl, but temporarily left the program in October of last year to seek assistance for a substance-abuse problem. He returned to school in January and won a battle with Trevone Boykin to regain the starting job, and had completed 17-of-30 passes for 175 yards with one interception over the team's first two games of 2013.

Boykin, who started nine games in Pachall's place as a redshirt freshman last season, will get the call under center for Thursday's Big 12 opener at Texas Tech. The dual-threat signal-caller threw for 133 yards and two touchdowns on 9-of-13 passing in relief against Southeastern Louisiana.

In 12 overall games in 2012, Boykin compiled 2,054 passing yards with 15 touchdowns and 10 interceptions while finishing third among TCU players with 417 rushing yards.