SANTA CLARA – Ian Williams admits it wasn't pretty last year in training camp when 331-pound left guard Mike Iupati came his way on a down block.

This year, he's better prepared for the avalanche. Williams, a nose tackle, said Wednesday that he's up to 320 pounds, 10 pounds heavier than he was at this point a year ago.

"I just feel better," he said. "I'm actually heavier, but I feel lighter on my feet. My technique feels better, and that's from all the sessions with the strength staff and Coach T."

Coach T is assistant coach Jim Tomsula, who once again has a full stable of talented youngsters along the defensive line. Last season, the 49ers kept seven linemen on the 53-man roster. That's a lot for a 3-4 defensive team, and the 49ers have been looking for creative ways to keep them all this year.

Demarcus Dobbs and Will Tukuafu, for example, have spent big chunks of the spring and summer practice sessions on offense. Dobbs has even gone so far as to change his practice jersey from No. 92, a defensive lineman's number, to No. 40, which tight ends can wear.

He's looked comfortable at his offensive position, so comfortable, in fact, that defensive coordinator Vic Fangio was asked if he was worried about losing the second-year player to the offense.

"He is getting better as a tight end, and I think he's a viable option for us as a tight end," Fangio said. But he said Dobbs is still primarily a defensive player, and likely will enter Friday's preseason game quickly as Justin Smith's backup at right defensive end.

Williams, meanwhile, is the least versatile of the young linemen. He's taken the lion's share of his snaps at nose tackle, which would seem to make him vulnerable on cut-down day.

The second-year player, however, has two things going for him.

First, both the starter at nose tackle, Isaac Sopoaga, and his backup, Ricky Jean Francois, are in the final year of their contracts. Second, Williams has had several strong practices this week and also stands to see a lot of playing time Friday.

Said Williams: "I don't think about the numbers. I just go out there every day and prove why I should be here and why I should be on the team. That's all I'm worried about."

Gold mettle performance – Safety Cory Nelms got another brief, excused absence Wednesday, this time to watch girlfriend T'erea Brown run in the finals of the 400-meter hurdles in London. Brown finished sixth, but Nelms wasn't disappointed.

"I'm definitely proud of her," he said. "I'm definitely sure she went out there and did her best. I'm thinking … peaking two times back to back, that's a lot on your body. Maybe that's all she had this year."

Nelms said his heart was "pumping out of my chest" as he watched the race.

The two started dating in 2008 at the University of Miami. Both were on the track squad. Nelms also was a walk-on on the football team.

He said he expects to see Brown, 22, on the Olympic medal stand in Rio de Janeiro in four years. "This is only her second year as a pro," Nelms said. "She'll definitely get stronger, get faster and just mature."

Et cetera – Fangio said he hadn't determined the playing time for his defensive starters Friday but that Aldon Smith might see more snaps than the rest. Smith is playing outside linebacker this year after mostly lining up as a defensive end in 2011.

• Rookie running back La-Michael James was back at practice after missing Tuesday's session with an illness. Rookie center Jason Slowey and cornerback Curtis Holcomb also were on the field.

• Wide receiver Kyle Williams was banished to the sideline during practice after getting in a scuffle with cornerback Deante Purvis. Williams and coach Jim Harbaugh huddled for a minute after practice.

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