49ers key matchup No. 2: Aldon Smith vs. Martin

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49ers key matchup No. 2: Aldon Smith vs. Martin

This is the second part in a series that spotlights three 49ers-Dolphins matchups to watch Sunday, 1 p.m. (CBS), at Candlestick Park.

49ers ROLB Aldon Smith vs. Dolphins LT Jonathan Martin

Tale of the tape
Smith (99): 6-foot-4, 258 pounds, second season, Missouri
Martin (71): 6-foot-5, 312 pounds, rookie, Stanford

Aldon Smith is closing in on Michael Strahan's NFL record of 22.5 sacks in a single season. With a league-leading 17.5 sacks, Smith needs five sacks in the final four games to get there.

Smith figures to be a focus each week. And on Sunday, he appears to have a significant advantage as he goes against Miami Dolphins rookie Jonathan Martin, who makes his first start on the left side after starting at right tackle up to this point.

Martin, whom the Dolphins selected in the second round of the draft, was originally projected as a mid-first-round selection. But his stock took a hit when he hoisted 225 pounds on the bench press just 20 times at the NFL scouting combine.

Martin played for 49ers coach Jim Harbaugh during his college career at Stanford.

"He was a good player for us at Stanford," Harbaugh said. "He's been doing a good job his entire rookie year, and to make the switch from right tackle to left tackle, he's adapted and doing a good job. With losing their left tackle, he'll be called on this week."

Martin takes over at left tackle after Dolphins All-Pro Jake Long was placed on injured reserve with a season-ending torn triceps. Defensive tackle Justin Smith described Martin this week as a "serviceable tackle in this league."

Martin will need to muster every bit of strength, as well as quickness, to keep up with Aldon Smith, who has demonstrated a wide array of moves as an every-down outside linebacker in his second NFL season. Smith already has recorded more sacks in his first two seasons than any other pass-rusher since the NFL began tabulating sacks in 1982.

"Some guys can get close but not finish," 49ers defensive coordinator Vic Fangio said. "Those guys can get close and finish. It takes a special skill set. You've got to have something special, one way or another, either one thing or two things. In Aldon's case, he's got length. He's got slipperiness. He's got some strength."

Agent: 49ers to re-sign running back DuJuan Harris

Agent: 49ers to re-sign running back DuJuan Harris

PHOENIX – Free-agent running back DuJuan Harris will re-sign with the 49ers, his agent said.

Harris, 28, appeared in 10 games for the 49ers last season with one start. He rushed for 138 yards on 38 attempts. He also caught eight passes for 115 yards.

Harris has also seen time with Jacksonville, Green Bay and Seattle in his four-year NFL career.

The 49ers did not tender Harris as a restricted free agent, but agent Andy Simms revealed his client will re-sign with the 49ers via Twitter. Wide receiver Jeremy Kerley and defensive lineman Chris Jones are the only other free agents the 49ers have re-signed.

Bruce Allen: Kirk Cousins will play for Washington in 2017

Bruce Allen: Kirk Cousins will play for Washington in 2017

PHOENIX – Washington quarterback Kirk Cousins will continue to be Washington’s quarterback for the 2017 season, according to team president Bruce Allen.

“That’s why we franchised him, yes,” Allen said during an interview with CSN Mid-Atlantic at the NFL owners meetings.

Cousins and Washington did not reach agreement on a multi-year contract extension before the start of the free-agent signing period. Washington tagged Cousins as the organization’s exclusive franchise player, taking him off the free-agent market for any interested clubs, such as the 49ers.

Cousins is set to earn $23.94 million in 2017, unless the sides agree to a new deal before the July 15 deadline. The price for Cousins to be franchised again in 2018 would be $34.47 million.

"We’ve had a lot of dialogue," Allen said. "He signed his tender. Obviously, we have an option for the ’18 season. Our goal from the beginning has been long term. I'm still hopeful and confident we'll do it."

The 49ers with new coach Kyle Shanahan are expected to be interested in Cousins, but there have no trade talks with any teams, Allen said. Shanahan was Washington's offensive coordinator under his father, then-head coach Mike Shanahan, for Cousins' first two NFL seasons.

"I can't keep up with the rumors," Allen said. "Kirk and I have talked almost a dozen times this offseason, and we get to laugh when we hear these different rumors. We haven't talked to anyone."