Another day closer to the regular season, another battle for playing time coming into focus.
Veteran Nnamdi Asomugha has gained the edge in the 49ers No. 3 cornerback competition, defensive coordinator Vic Fangio said Tuesday, meaning that the three-time Pro Bowler would enter the game when the opposition brings a third wide receiver onto the field.
"He's done well in his reps that he's had in the game and in practice," Fangio said. "Particularly the last two or three weeks, he's played much better."
Asomugha has been in a dead heat with fourth-year pro Tramaine Brock for the third spot. Perrish Cox was also in the mix. Both of the latter players are still in contention to be among five or six cornerbacks overall when San Francisco cuts its roster to 53 players on Saturday.
PHOTOS: 49ERS ROSTER AT 75
It remains to be seen how much the trio will play in the 49ers preseason finale on Thursday night in San Diego against the Chargers. Asomugha's performance in the team's previous exhibition, on Sunday against the Minnesota Vikings, cemented Fangio's call.
There are other factors at work.
"Brock was nursing an injury prior to the third preseason game and the second preseason game, which allowed Nnamdi to move ahead," Fangio said. "Now Nnamdi's nursing a little injury. It's a little bit unsettled because of the injury situation, more so than anything."
Asomugha, 32 and entering his 11th season, had given Fangio reason to question "whether he still (had) some gas left in his tank" earlier on, in training camp. The free-agent addition's ability to play on the right side of the defense – and the left, where Fangio inserted him 10-14 days ago – added to his value.
It's Asomugha's vitality -- more so than versatility -- that has him slated to play behind starting cornerbacks Carlos Rogers and Tarell Brown. Fangio sounded confident that No. 24, who was sporting a blue, non-contact jersey at Tuesday's practice, can handle the workload when the games count.
"He's still playing at a good enough level to be a major part of our defense," Fangio said. "If he's the third corner, he's going to get somewhere between – if you use the last two years as a barometer – 50 and 65 percent of the snaps. That should be a good enough gauge."