ENGLEWOOD, Colo. (AP) The new hybrid offense that mixes Peyton Manning's skills and Gary Kubiak's philosophies needs more work, or at least Manning's top targets do.

Dropped passes and penalties prevented the Broncos quarterback from finding the end zone or even a rhythm in his 2015 debut Saturday night.

Demaryius Thomas, Owen Daniels and James Casey dropped third-down passes that killed drives, and Virgil Green's holding penalty stalled Denver's most promising possession before backups engineered a 14-10 victory over the Houston Texans.

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So, Manning didn't get the work, especially in the red zone, that he so desperately wanted after sitting out Denver's preseason opener against Seattle.

''Sure, you would like to score four touchdowns in four possessions,'' Manning said. ''... (but) we had some self-inflicted wounds that kind of kept us from getting into a rhythm and continuing with some drives.''

In 19 snaps, Manning moved the Broncos 67 yards over four possessions that all ended in punts.

Manning insisted it wasn't all bad, however.

For one thing, he figures the footballs and flags won't keep hitting the turf.

''I don't see those things being a constant for us this year,'' Manning said. ''I think we will do a good job in that category.''

And his young O-line featuring four newcomers, a pair of rookies and a practice squad graduate held up well in the noise and with the no-huddle.

''I thought the protection was good the whole time I was in there,'' Manning said.

Manning said what pleased him the most was watching rookie quarterback Trevor Siemian's game-winning 26-yard touchdown toss to Corbin Louks in the final minutes.

''The longer you play, the more you certainly appreciate the young guys trying to earn a spot on the team and there are a lot of guys fighting for jobs out there,'' Manning said. ''So, it's really good to see some guys make plays out there to help us win the game.''

Siemian has clearly surpassed Zac Dysert as Denver's third QB option behind Manning and Brock Osweiler, who threw a 57-yard touchdown pass to Bubba Caldwell for the Broncos' other points.

After missing the entire offseason program while recovering from a torn ACL that occurred in his final college game, Siemian is 12 for 16 for 179 yards and a TD this preseason.

His passer ratings of 118.8 and 130.8 have been Denver's best so far.

Siemian's stats at Northwestern didn't stand out. Splitting snaps for the Wildcats, he threw for 27 TDs and 24 interceptions in four years. But general manager John Elway raved about Siemian's technique and said he could be a late-round gem.

Siemian's solid play in the preseason might force the Broncos to keep three quarterbacks on their 53-man roster, something Kubiak has preferred not to do over his career, because sneaking him onto the practice squad might prove difficult now.

Kubiak, however, wasn't about to hide him this month.

''We've got to find out what he is. There's no hiding anybody. We're going to let him play,'' Kubiak said. ''The question of him coming out, there wasn't much action. He's kind of split time with another quarterback. Like I said, we knew he would throw the ball well, and the thing that's been impressive is that some of the other stuff is starting to take place.''

Like the poise he displayed in driving Denver 92 yards in seven plays for the winning score.

''It's the preseason stage, but you're still on the road and backed up on your own 8-yard line to start a big drive,'' Kubiak said. ''So, he continues to do those things and he's trying to prove that he can play in this league, not only make this team.''

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Follow AP Pro Football Writer Arnie Melendrez Stapleton on Twitter: http://twitter.com/arniestapleton