HOUSTON (AP) Denver coach Vic Fangio expected to see some improvement from rookie quarterback Drew Lock on Sunday in his second career start.

He didn't dream he'd see this big of a jump.

Lock threw for 309 yards and three touchdowns, Kareem Jackson had an interception and returned a fumble 70 yards for a touchdown against his former team as the Broncos built a huge first-half lead and coasted 38-24 over the Houston Texans.

Fangio at first joked that the second-round pick out of Missouri was “just OK” before getting serious.

“He played, obviously, very well,” Fangio said. “Made a great jump from Week 1 to Week 2, which is what you’re hoping for. I thought he threw the ball much, much better than he did last week. I don’t think he missed many today. To do that on his first road start against a team that’s going to be in the playoffs makes it even better.”

Lock, who made his NFL debut in a win over the Chargers last week, threw for 235 yards with three TDs in the first half. It was the most yards passing in a first half by the Broncos since Peyton Manning had 282 in Week 5 of 2014.

“We were ready to rock and roll from the get-go," Lock said. “We were fired up. We were ready to go. It was exciting to be a part of.”

The Broncos (5-8) scored on their first five possessions to build 38-3 lead early in the third quarter. They scored more than 24 points for the first time since Oct. 19, 2018.

Houston's hold on the AFC South took a hit as the Texans (8-5) came out flat in a terrible first half a week after downing the Patriots 28-22 for their first win in the series since 2010. Tennessee (8-5) beat Oakland later Sunday to move into a tie with Houston for first place in the division.

“I don't think there was anything very good,” Houston coach Bill O'Brien said. “I take full responsibility for that. Just did not have this team ready to play. I thought I did, but I was wrong.”

Deshaun Watson threw for 292 yards with one TD pass and two interceptions after throwing three touchdown passes and grabbing his first career TD reception in a stellar performance against New England.

The Broncos took an early lead when Lock threw a 14-yard touchdown pass to Noah Fant with about 7 1/2 minutes left in the first quarter. Fant, who finished with 113 yards receiving, had a 48-yard reception earlier in that drive.

Keke Coutee, inactive for the past two games despite being healthy, grabbed an 8-yard reception on Houston's next drive but fumbled. Jeremiah Attaochu picked up the ball and handed it off to Jackson, who dashed 70 yards for the score against the team he spent the last nine seasons with.

Jackson wanted to treat this like any other game but admitted to getting a little emotional when he arrived at the stadium and began seeing so many familiar faces.

“It’s all about me being a piece of the puzzle,” he said. “I didn’t want to make it all about me and my return here. We had to come here and execute as a team. It’s all about executing the day, and I felt like we did that in all three phases.”

Denver pushed the lead to 21-0 in the second quarter when Lock connected with Jeff Heuerman on an 8-yard pass. Lock had completions of 37 and 25 yards on that drive.

The Texans went on fourth-and-1 from their 34 with two minutes left in the first half and Watson's pass was tipped at the line and fell incomplete to give the Broncos a short field. They took at advantage when Royce Freeman caught a 3-yard touchdown pass to make it 31-3 at halftime. Houston's Lonnie Johnson had two defensive holding penalties on that drive.

Phillip Lindsay pushed Denver's lead to 38-3 with a 1-yard run early in the third quarter.

DeAndre Hopkins gave the Texans their first touchdown on a 43-yard reception on their first drive of the second half.

Tashaun Gipson intercepted Lock near the goal line on Denver's next drive and returned it 26 yards. The Texans made it 38-17 early in the fourth quarter when Watson leaped into the end zone at the end of a 6-yard scramble.

Houston got a stop and Watson converted a fourth-and-19 with a pass to Hopkins on the next drive before his pass on fourth-and-3 was tipped three times and intercepted by Jackson to end any hope of a comeback.

Watson added another touchdown run with 32 seconds left.

INJURIES

Broncos: DE Dre'Mont Jones injured his ankle in the first quarter and didn't return. ... Fant left in the second half with a foot injury.

BUZZ LIGHTYEAR

Lock's teammates joked last week that the big wristband he wore with the plays on it looked like the laser beam that Buzz Lightyear, the animated star of Disney's “Toy Story” movies, wears on his forearm. So this week he decided to have a little fun with their mockery and pretended to shoot laser beams out of his wristband after throwing a touchdown pass against the Texans.

“It was definitely a lot of fun with Buzz Lightyear this week, blew up on Twitter to where the offensive line (said) we should shoot the laser after you score a touchdown,” Lock said. “All right you want to do it, we'll do it. We fully embraced it.”

The 23-year-old Lock wasn't born when the first movie came out in 1995, but he's caught up on all four movies since then.

“Buzz is older than me, but we’ve got to bring back some legends sometimes,” he said.

LINEBACKER COSTUMES

Houston's linebackers continued their ritual of wearing themed outfits to games this week by dressing up like characters from the movie “Dodgeball.” The group has also dressed as members of a swat team, Teenage Mutant Ninja Turtles, Super Mario Bros characters, and in jerseys from the movie “Space Jam.”

UP NEXT

Broncos: Visit the Chiefs next Sunday.

Texans: Visit the Titans next Sunday.

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