Rapid Reaction: Chargers 20, Cowboys 7

ARLINGTON, Texas -- The second preseason game is over and the Cowboys' second and third units had their issues Sunday night in a 20-7 loss to the San Diego Chargers.

There was no late fourth-quarter magic from quarterback Stephen McGee, who played the entire second half. But starter Tony Romo led the first-team offense on an 11-play, 80-yard scoring drive in the second quarter for the first touchdown of the preseason for the first team.

What it means: The Cowboys' first-team offense did score a touchdown, but the second and third team offensive lines struggled Sunday night. Pass protection was the biggest concern. It's something that will need to be addressed quickly. The first-team defense got some extra playing time, much like the offense, and gave up 10 points. There were some notable performances from Gerald Sensabaugh (forced fumble), DeMarcus Ware (sack) and Abram Elam (tackle for loss).

First-team offense gets touchdown: One of the issues with the first-team offense has been scoring touchdowns. They were only able to manage a field goal in the preseason opener vs. Denver. Sunday night vs. San Diego, Romo connected with Jason Witten on a 6-yard touchdown pass for the first touchdown for the first-team offense. Overall, Romo completed 8-of-12 passes for just 58 yards, one touchdown and one interception. Romo underthrew a pass to Kevin Ogletree. Running back Felix Jones had another strong effort. He rushed for 56 yards on just seven carries. He had a 22-yard run among his highlights.

Backup line struggles: There was an ugly sequence of the third quarter when left guard Pepa Letuli was benched during the middle of a drive. David Arkin, who was praised all week for his work with the first-team offensive line, allowed McGee to get sacked, causing a fumble, which resulted in a turnover. Right tackle Sam Young and left tackle Jermey Parnell struggled at times. Even Kevin Kowalski, who replaced Letuli, had some issues.

Replay challenges favor the Chargers: Norv Turner challenged two plays and won, earning a touchdown for running back Ryan Mathews and turning a Sensabaugh interception into an incompletion. With Turner winning the two challenges, he picked up an extra one. In the fourth quarter, Jason Garrett challenged a fumble by Stephen McGee, but the play was upheld.

Tanner moves past Miller: Lonyae Miller was the star of training camp, then the preseason started and he's struggled. He can't find holes and when there are none, he doesn't show good vision trying to find room. Phillip Tanner, meanwhile, is hitting holes and moving well. He had gains of 10 and 14 yards in the second half. Miller, while struggling to run the ball, also fumbled after catching a pass. Tanner had his best play called back after he ran for an apparent touchdown but lost his helmet breaking a tackle. A new rule says if a player's helmet pops off, the play is dead. A penalty nullified the play anyway.

What's next?: The Cowboys will begin a four-week road swing when the team visits the Minnesota Vikings Saturday night. After that, the Cowboys play the Miami Dolphins, then it's off to start the regular season with two road games.