SANTA CLARA – Until Tuesday, one of the men standing between the 49ers' Aldon Smith and the NFL's single-season sack record was a former No. 1 overall draft pick, a four-time Pro Bowler and the leader of Miami's offense.

The Dolphins, however, placed left tackle Jake Long on injured reserve after he tore his triceps last Sunday in a loss to New England. Taking his place for Sunday's game against the 49ers is a far less heralded offensive tackle, rookie Jonathan Martin, who played for 49ers coach Jim Harbaugh at Stanford.

"He's a serviceable tackle in this league," defensive end Justin Smith said of Martin. "It's definitely not Long in there. But there's things you can do. You can chip. You can slide the line. You can do some more bootlegs, which is a big part of their offense as well, to help him out. We kind of anticipate all those type of deals going on."

Justin Smith has been Aldon Smith's main accomplice as the latter tries to break former New York Giants defensive end Michael Strahan's record set in 2001. Smith leads the league with 17 1/2 sacks and needs 5 1/2 in the last four games to pass Strahan.

"He's a beast," Martin told Miami reporters Wednesday when asked about Aldon Smith. "Also, No. 94, (Justin) Smith, has had some plays. So the (right) side of that defense is really talented. It will be a big challenge."

Aldon Smith seems to have a shot at the record, especially with Long's absence. The Dolphins had allowed the 14th fewest sacks in the league with Long in the lineup, and he led Pro Bowl voting at his position.

After the Dolphins, the 49ers play New England, the fourth-best team when it comes to pass protection, followed by Seattle, which ranks ninth.

They finish the season against Arizona, which has done the poorest job protecting its quarterbacks. The Cardinals have given up 48 sacks, and Aldon Smith had two in the teams' game Oct. 29.

"(Aldon is) chasing history, and he's going to keep doing what he does – and that's to make the plays to help the team win," Justin Smith said. "And if, along the way, he gets the record, then so be it. We're all pulling for him, hope he gets it, and we're pretty confident he will."

Martin, Miami's second-round draft pick, started the first 12 games at right tackle before sliding over to the left side when Long went down 11 plays into Sunday's game. He allowed a sack and four quarterback hurries in a 23-16 loss.

Miami's own pass-rushing ace, Cameron Wake, has spent the year getting Martin up to speed.

Wake said the two often work together after practice and that he's gone head-to-head with the rookie more than any player on the Dolphins.

"I watched him – literally from the day he got here – mature and grow into the game," Wake said on a conference call. "He's playing like a veteran. We don't have any rookies anymore. That's what we talk about at this facility. There are no more rookies. You've been out there, you've been playing, you've got to step up."

Martin played left tackle at Stanford. And while he admitted it took time to adjust when he moved back to that side of the line Sunday, it's been more natural during practice this week.

"I feel pretty darn comfortable," Martin said. "I played that position for a long time in college, so I feel good."

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