Of all the challenges now confronting Houston Texans quarterback Brock Osweiler, one of the most significant involves his confidence, according to league sources.

NFL executives and coaches who have watched Osweiler play believe he has lost confidence, and it has affected his play. They pointed to one particular throw during Monday night's loss to his former team, the Denver Broncos, when Osweiler had one of his tight ends wide open and missed him by about 3 yards. One source said he believed Osweiler's inaccuracy is a direct result of his lack of assurance in his abilities.

Brock Osweiler is completing 58.2 percent of his passes this season with 8 touchdowns and 8 interceptions. Dustin Bradford/Getty Images

Monday night's loss was Osweiler's first game in Denver since leaving to sign a four-year, $72 million contract with the Texans during the offseason. He finished 22-for-41 for 131 yards without a touchdown and also fumbled early in the fourth quarter, putting the game out of reach for Houston.

He has completed 58.2 percent of his pass attempts this season, throwing eight touchdowns and eight interceptions.

Texans coach Bill O'Brien is one of the league's top quarterback gurus, but also is very demanding. Regardless of whether O'Brien's style is affecting Osweiler's performance, those who have watched the Texans quarterback believe his confidence has taken a hit.

Information from ESPN Texans reporter Sarah Barshop was used in this report.