After a bye week of mostly talk, Mike Singletary got back to work with some hands-on instruction. During 49ers practice Tuesday, he wrapped an arm around offensive lineman Chilo Rachal, who was running out of gas, and delivered a brief pep talk.

Singletary reminded the rookie that the key to the fourth quarter is the ability to fight through fatigue.

"I mean, that feels good," Rachal said later. "He's pushing me. He's looking out for my best interest. He makes me want to work harder."

Singletary has mentioned Rachal several times as he talks about transforming the 49ers into a more physical team. Tuesday was certainly a more physical practice, which explains why Rachal and others were gasping for air.

Singletary also has the first-team offense take on the first-team defense, a rare showdown usually reserved for training camp. Because the 49ers don't play again until Monday, they could afford to delay their scout-team work an extra day.

"We're not going to get another day like today the rest of the season," Singletary said. "How do we get the most out of today?

"It's more camaraderie. It's kind of a 'Welcome back. Get your mind right and get ready to go."'

Rachal spends time at right guard and right tackle. The second-round draft pick has yet to take the field and there is no guarantee that he will do so when the 49ers resume play against the NFC West-leading Arizona Cardinals.

But Singletary keeps hinting that the No. 39 overall pick is getting closer to making a contribution. The new coach seems to have taken a special interest in the rookie and has taken him under his wing.

"He's a good kid," Singletary said. "He wants to play and he wants to do all the right things. When you see that as a coach, you really want to come beside a guy and try to point out things he needs to do more of, things he needs to do less of."

Rachal spent the first two games on the inactive list. He has the dreaded "DNP" on his stat sheet in each of the six games since.

He and first-round pick Kentwan Balmer, No. 29 overall, lead a draft class that has made little impact. The six picks have combined for one start — receiver Josh Morgan, the sixth-round choice, got the nod in Week 8 against Seattle.

Rachal, 22, acknowledged that his rookie season has been a learning process. But he said he is eager to show what he can do "the first chance I get." The 6-foot-4, 315-pound lineman never allowed a sack during 21 starts at USC. He was also the Trojans' fastest offensive lineman and clocked a 4.92 in the 40-yard dash this year.

Rachal has discovered, however, that those workout stats don't count for much.

"NFL guys are smarter," Rachal said. "In college, you can get away with a lot of things just based on size and strength. But here guys are more strategic. They know that if you're leaning forward, they're going to swing you. If you're overset, they're going to go on the side. Players have more attention to detail."

To earn a spot on the field, Rachal needs to show consistency — and maybe some improved conditioning. When Singletary pulled Rachal aside during practice Tuesday, it looked like a heart-to-heart. It turns out that the coach was just keeping his player upright.

"What I did is I kept him from cramping up," Singletary said with a laugh. "Bending over, you don't want to do that when you're tired. You'll start locking up."