When the first betting lines were released on Sunday, No. 1 Alabama was an eight-point favorite over No. 9 Tennessee.

However, as it stands on Thursday, the Crimson Tide are a 13-point favorite over the Vols, according to Las Vegas sports books.

AL.com spoke with a betting expert about why the line has moved so much. ESPN’s David Purdum attributed the big shift to the fact that offshore sports books that don’t take in as much money as Las Vegas are often the first to release the lines:

“They put them out there as kind of a publicity thing, but they might take only a couple hundred dollar’s worth of bets,” Purdum said. “Those early numbers are not really indicative.”

Still, the movement on the Tennessee-Alabama line was unusual for this point in the season, according to the expert:

“That is a pretty significant move,” Purdum said, “especially for this time of year when we feel like teams or the power rankings should have adjusted to have a good feel for the teams.”

A number of injuries (and the recent dismissal of DL Danny O’Brien) may help explain the movement of the line, too.