HOUSTON -- For most rookies, an NFL debut is a blur of nerves and adrenaline. For Marlin Klein, it was a moment years in the making, and he made it count. The Houston Texans' second-round pick out of Michigan played just 11 snaps in Thursday night's preseason opener against the Los Angeles Chargers, but that was enough to leave a vivid impression on his head coach. Klein, a tight end born in Germany who moved to the United States at 16 to pursue football, caught a 31-yard pass on the Texans' first drive, a play that showcased his athleticism and fluidity. "I thought he really shined today," DeMeco Ryans said. "Everybody saw the pass that he caught. It's where I see him where he can excel for our offense and just open the offense. His catch radius is tough to guard." But Ryans didn't stop at the reception. He also noted Klein's work in the run game. "Watching him blocking in the running game, I saw him finishing some blocks there exactly how we want it done," Ryans added. "So a ton of positives there for him." For Klein, the moment carried deep personal significance. "It's something that I've been dreaming about ever since I was a little kid," he said. "It was the reason why I moved over here to the States to play in a game like this, so it meant a lot to me." The game itself, a 27-7 loss for the Texans, was a typical preseason affair with most starters sidelined. Houston's C.J. Stroud and Los Angeles' Justin Herbert did not play. Instead, the Chargers were powered by Amar Johnson, an undrafted free agent entering his second season, who ran for two touchdowns and added a 55-yard reception. Johnson scored on a 7-yard run in the second quarter to put the Chargers up 10-7, a drive led by backup quarterback Trey Lance. He added a 1-yard touchdown early in the fourth quarter and ran in the two-point conversion to push the lead to 21-7. The 55-yard catch, from D.J. Uiagalelei, set up that scoring opportunity. "He looked like he had some burst and some speed," Chargers head coach Jim Harbaugh said. "He's got that in him, and it was good to see him show that tonight." For the Texans, Davis Mills started at quarterback and played with the starting offensive line on the first series, throwing a 5-yard touchdown pass to Jared Wayne. He was then replaced by Graham Mertz, but Mertz suffered a knee injury late in the second quarter with two seconds left. Ryans confirmed Mertz injured an ACL, with further evaluation pending. Mills returned to finish the game, completing 9 of 15 passes for 82 yards. Lance, the third overall pick in the 2021 draft, went 12 of 20 for 164 yards with an interception. Uiagalelei later sealed the win with a 3-yard touchdown pass to Devonte Ross with about 10 minutes remaining. Several other rookies also made their debuts. Texans first-round pick Keylan Rutledge, the 26th overall selection, started at center alongside the rest of Houston's starting offensive line. Defensive tackle Kayden McDonald, taken by the Texans in the second round, impressed in limited snaps. On the Chargers' side, defensive end Akheem Mesidor, the 22nd pick, and second-round offensive lineman Jake Slaughter both made plays. In the kicking game, Chargers Pro Bowler Cameron Dicker connected on field goals of 34 and 48 yards but missed an extra point in the fourth quarter. Houston's regular kicker Ka'imi Fairbairn did not play, so undrafted free agent Chris Freeman handled duties. He made an extra point but missed a 61-yard field goal as the first half ended. Both teams now look ahead to Week 2 of the preseason. The Chargers will host San Francisco next Thursday night, while the Texans host Las Vegas.