BOX SCORE

HOUSTON – The 49ers’ top two running backs appear set.

And the competition for the 49ers’ No. 3 running back appears to remain unresolved after the 49ers’ 16-13 loss to the Houston Texans in the second exhibition game of the summer for both teams on Saturday night.

Third-string quarterback Nick Mullens looked as if he pulled off his second fourth-quarter rally in two weeks, as he moved the 49ers into position for Robbie Gould’s 41-yard go-ahead field goal with 1:41 remaining in regulation.

But the 49ers' third-string defense allowed the Texans to drive 75 yards for the winning points, which came on Joe Webb's 41-yard touchdown pass to Vyncint Smith in the closing seconds.

A lot of the focus entering Saturday’s game was on the running backs, and for good reason.

Jeremy McNichols started and played most of the first half and into the second half. He did not find much room to run against a Texans defense that did not feature either J.J. Watt or Jadeveon Clowney.

McNichols, who spent last season on the 49ers’ practice squad, finished with just 28 yards on 10 rushing attempts. He caught three balls for 19 yards and also dropped a pass.

Joe Williams, a fourth-round draft pick in 2017, was the only other 49ers running back who saw action in the first half. He did not have much success, either. Williams gained 18 yards on eight carries. He caught two passes for 14 yards. But Williams also failed to hang onto a short pass from Nick Mullens, resulting in an interception.

Veteran Alfred Morris did not play. The 49ers signed Morris this week after Jerick McKinnon (calf) and Matt Breida (shoulder) were ruled out for the remainder of the preseason with injuries.

Raheem Mostert was the No. 3 running back last season, and he appears to remain in that position due to his contributions on special teams. Mostert appeared on the 49ers’ No. 1 kickoff and kickoff return teams.

He also lined up as a gunner on punt coverage with Aaron Burbridge on the other side. Burbridge and Mostert are likely the 49ers’ top two special-teams players.

Mostert demonstrated his prowess on special teams with a bone-jarring tackle of Houston return man Tyler Ervin for no gain on a punt return. However, Mostert was hit with a questionable unnecessary roughness penalty for lowering his head and initiating contact.

Here are some other notes from the game...

--Quarterback Jimmy Garoppolo played the 49ers’ first 21 offensive plays, spanning two possessions, and completed 10 of 12 pass attempts for 136 yards with one touchdown and one interception.

Garoppolo hit Marquise Goodwin on three completions for 61 yards, and tossed a 2-yard touchdown pass to Trent Taylor. His night ended when his high throw intended for Dante Pettis was deflected into the hands of Texans cornerback Johnson Bademosi.

--Defensive lineman Jeremiah Attaochu was also penalized 15 yards for lowering his head to initiate contact. Attaochu was flagged for making contact against an offensive tackle as a pass rusher.

--Texans cornerback Kevin Johnson fell hard after attempting to defend a deep pass to Goodwin. After receiving several minutes of medical attention, Johnson got to his feet and walked under his own power to the locker room. Johnson was diagnosed with a concussion.

--Mike Person started at right guard and played the first series for the 49ers. Joshua Garnett entered and played the remainder of the first half.

--Linebacker Reuben Foster and right cornerback Jimmie Ward played the entire first half. Foster had a team-leading four tackles and broke up a pass. Ward had three tackles.

--Reserve guard/center Erik Magnuson sustained a hamstring injury near the end of the third quarter and did not return. Magnuson had a difficult time walking from the sideline to the 49ers’ locker room.

--Emmanuel Moseley intercepted a pass that was deflected by fellow rookie cornerback Tarvarius Moore.

--Cornerback Richard Sherman, who returned to practice last week after mssing time with a hamstring strain, did not suit up for the game. He went through warmups but was held out of action. He did not practice against the Texans on Wednesday and Thursday, either.

--In addition to Sherman, the following 49ers were held out of the game due to injuries: running backs Jerick McKinnon (calf) and Matt Breida (shoulder), wide receiver Max McCaffrey (foot), tight end George Kittle (shoulder), offensive lineman Garry Gilliam (concussion), defensive linemen Solomon Thomas (concussion) and Arik Armstead (hamstring), linebacker Malcolm Smith (hamstring), cornerback K’Waun Williams (ankle), and safety Marcell Harris (hamstring).