The pro football season is preparing to kick off, but one Las Vegas bookmaker has already picked the Denver Broncos to win Super Bowl XLIX.

Wynn Sports Book Executive Director John Avello gave the NFL team 5-1 odds, with the defending champion Seattle Seahawks right behind at 7-1.

The NFL season opens 8:30 p.m. EDT Thursday with the Green Bay Packers hosting the Seahawks.

Avello said on CNBC's "Halftime Report" that after each Super Bowl, it's his job to "evaluate each team, assign odds to them and then put a little hold percentage there for the house."

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Avello added that despite wide receiver Wes Welker's four-game suspension after testing positive for a banned substance, the Broncos' talent pool ran deep.

"Denver still has ... very good personnel on the team," he said. "You can't make any drastic adjustments on that alone."

The bookmaking business in Las Vegas was a $3.2 billion business last year, with football betting accounting for 60 percent of that figure, split evenly between the NFL and college football, according to Avello.

"There's more college games, so therefore the players get to pick and choose more than the NFL, who only has 16 games per week," he said. "And so therefore, we're more vulnerable to college football than we are pro football."

Avello's next top three Super Bowl favorites were the San Francisco 49ers (8-1 odds), Green Bay Packers (9-1) and New England Patriots (10-1).

—By CNBC's Bruno J. Navarro