Derrius Guice had a nice game for the Redskins in his first extended action since tearing his ACL in last year’s first preseason game. (Jonathan Newton/The Washington Post)

Derrius Guice hopped in place in the end zone, holding both hands in the air to mimic the signal for a touchdown. He was hoping for it, begging for it, but a yellow flag lay on the turf at Mercedes-Benz Stadium. The diving score was called back because of a holding penalty on guard Ereck Flowers, but it was the lone pockmark on an otherwise exquisite return for the second-year Washington Redskins running back.

Washington beat the Atlanta Falcons, 19-7, on Thursday in its third preseason game, but the result was less important than the return of one of the organization’s key players. In his first game since he tore his ACL in last year’s preseason opener, Guice played the first four series and finished with 44 yards on 11 carries and four receiving yards on one catch while officially announcing his healthy return.

“It’s been a long time, bro,” Guice said. “I knew it was something I needed. I needed to get out there, get my feet under me, get some contact to really see where I’m at.”

The Redskins played most of their expected Week 1 starters for the majority of the first half as Guice, tight end Jordan Reed and wide receiver Paul Richardson Jr. made their preseason debuts. Unfortunately for Washington, the oft-injured Reed left the game and is in the NFL’s concussion protocol following a nasty helmet-to-helmet hit in the second quarter. The tight end had shined during training camp and preseason practices, but another injury brings back the biggest issue for the Redskins’ best offensive weapon. Reed continued to play after the hit, but Coach Jay Gruden said he developed symptoms after halftime.

Donald Penn started at left tackle in front of Geron Christian for the first time as the two continue to battle for the No. 1 job in the absence of Trent Williams, who is holding out. Flowers continued to get first-team reps at left guard in front of rookie Wes Martin, though he struggled and was beaten for a big hit on quarterback Case Keenum and was called for the hold that wiped out the Guice touchdown. On defense, first-round rookie edge rusher Montez Sweat got the start in front of Ryan Anderson.

The first series of the game was exactly what the organization had been waiting to see from Guice. He touched the ball on four of the first eight plays and showed why there was such excitement before the injury. The 2018 second-round pick’s first touch came on first down when he took a handoff to the left, cut back to the right and lowered his pads at the end of a seven-yard run.

The next touch showed everything in the Guice repertoire. He took a counter to the left and used a bit of speed to get to the corner. He then straight-armed cornerback Isaiah Oliver to the ground while turning upfield. Guice finished the run by throwing a shoulder into safety Keanu Neal instead of simply stepping out of bounds for six yards.

“When that corner came at me with the angle he took, I knew I had to give him an arm,” Guice said. “The safety, [I] played him in college [at LSU]. He went to Florida. I’m a little salty with Florida, so I had to give him a little shoulder. Safeties, they get big eyes when they see running backs on the sideline. They feel like it’s an open shot for them but not me. I’m ready. . . . Felt like a college run for me, for sure.”

That first series, an eight-play, 41-yard drive, ended with a 48-yard field goal from Dustin Hopkins to give Washington a 3-0 lead with 4:03 left in the first quarter.

Keenum failed to lead a touchdown drive in his half of action, finishing 9 for 14 for 101 yards and one fumble lost. He had a few strong throws, including a 16-yarder to Josh Doctson and a pair of 28-yard gains to Jeremy Sprinkle and Cam Sims, but there were drive-killing mistakes. The biggest was the fumble recovered by defensive end Takk McKinley when Keenum held on to the ball too long in traffic and took a hit from Deadrin Senat. Senat was credited with a sack as the ball floated straight to McKinley.

“The turnover was completely my fault,” Keenum said. “Poor decision. Held on to the ball too long. Just something I was trying to manipulate some coverage with my eyes. Something I don’t need to do. Silly mistake. I don’t need to put our defense in that situation.”

Atlanta needed just five plays after starting on the Washington 33-yard line for Ito Smith to punch in a five-yard touchdown run with 6:09 remaining in the second quarter to take a 7-3 lead.

The Redskins’ normally stout first-team defense allowed the Falcons to get down to the Washington 21 on an opening drive that was extended by a fake punt on the fifth play of the game, but Giorgio Tavecchio missed a 39-yard field goal to waste it. Atlanta quarterback Matt Ryan, a former MVP, finished 9 for 14 for 74 yards without a touchdown or interception.

Rookie quarterback Dwayne Haskins played the second half for the Redskins and continued to have his ups and downs. He finished 7 for 13 for 74 yards and had the opportunity for more but simply missed a few throws. Running back Samaje Perine scored on a three-yard run in the third quarter for the Redskins’ only touchdown three plays after Atlanta muffed a punt. Hopkins finished 4 for 4 on field goals to account for the rest of the scoring.