San Francisco 49ers

Marcus Martin’s injury serious; 49ers confident in Kilgore at center

What was supposed to have been a two-man battle to become the 49ers’ starting center this year never was much of a competition.

When training camp began, draft pick Marcus Martin was on the sideline with an ankle injury. Then just as he was starting to assert himself in preseason games, he suffered a knee injury that could keep him out until midseason.

Jim Harbaugh on Monday wouldn’t elaborate on the injury, which occurred in the fourth quarter Sunday when an opponent fell on the back of Martin’s legs, only that the third-round draft pick did not suffer a torn ACL. A league source said Martin suffered a dislocated kneecap and might miss eight weeks.

The 49ers are leaning toward keeping him on the active roster. Placing Martin on injured reserve would end his season.

That means Daniel Kilgore will start at center when the 49ers open the season against Dallas on Sept. 7 and that there will be a competition to be his backup. Both Adam Snyder and Joe Looney can play the position, Harbaugh said, and Snyder on Monday noted that he started four games there when he was with Arizona in 2012.

The 49ers did not make an effort to re-sign veteran Jonathan Goodwin, the team’s center for the last three seasons, in free agency. He was picked up by the Saints and is the front-runner to start in New Orleans this year.

Kilgore, meanwhile, has never started a regular-season game, but he’s been a steady presence at center throughout the preseason.

“He’s a very athletic center; he has a good combination of strength and quickness; he has a quick mind,” Harbaugh said. “He has done a good job of making the calls and understanding the system. He’s on a streak of not missing a call for ... I can’t remember the last time he missed a call. So it’s been good – been very pleased, knock on wood.”

Kilgore also hasn’t had a botched snap with quarterback Colin Kaepernick this preseason. They appeared to have one dubious exchange during a scrimmage against the Ravens, but it turned out that a running back inadvertently hit the shotgunned snap as he was running down the line of scrimmage.

Their chemistry grew partly because the two worked together when both were rookie backups in 2011.

In that way, Kilgore said he also has developed a good rapport with Looney, the team’s starter at right guard who was drafted in 2012. Before games, all of the backup offensive linemen, which in recent years included Kilgore and Looney, would practice together for three hours under the supervision of offensive-line coach Mike Solari.

“Every rep counts,” Kilgore said. “Joe’s been next to me for three years now, so there is that chemistry.”

Bethel-Thompson waived – To reach the 75-man limit, the 49ers waived seven players, including former Sacramento State quarterback McLeod Bethel-Thompson and wide receiver Devon Wylie, who is from Granite Bay.

Also waived were safety D.J. Campbell, tight end Kevin Greene, running back Jewel Hampton, punter Colton Schmidt (UC Davis) and linebacker Kion Wilson. All of the waived players are eligible for the practice squad.

As expected, the 49ers also placed seven players on injury lists. They include linebacker NaVorro Bowman and running back Marcus Lattimore. They are eligible to play after six weeks but don’t count against the 53-man roster until they are activated.

Additionally, the team released veteran wide receiver David Reed and linebacker Blake Costanzo. The 49ers must trim the roster to 53 players by Saturday afternoon.

Grass-roots effort – The 49ers ripped up the grass field they put down less than 72 hours earlier and are installing a new, hopefully more permanent, playing surface.

Backhoes were brought in, presumably to dig up and remove some of the sand that had served as a layer below the grass. The composition of soil and sand was suspected to have been the problem with the original field, which was torn up Thursday. After consulting experts, the 49ers concluded there was too much sand in the mix, preventing the grass from taking root.

That grass was coming up in chunks during a practice last week and wasn’t repairing itself as advertised. The 49ers put in a thicker sod before the Chargers game, but it never was viewed as a permanent solution.

The team wanted new grass installed throughout the field – from one row of seats to the other – in time for the Sept. 6 soccer match between Mexico and Chile. That will serve as a test run of sorts for the 49ers’ Sept. 14 home opener against the Bears.

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