Guard Mike Iupati believes an “easy fix” to his technique will correct his pass-protection problems in  the 49ers’ 21-7 exhibition win Sunday over the Chargers. Iupati allowed a fumble-causing sack and another hit on quarterback Colin Kaepernick in the first few series. “It hurts because you always want to be on top of your game,” said Iupati, a fifth-year veteran who’s received Pro Bowl honors the past two seasons. “You learn from it and move on.” What did Sunday’s issues prompt Kaepernick to tell him? “He says, ‘C'mon Mike, do better’, ” Iupati relayed Monday. “Sometimes you lose some, sometimes you win some,” Iupati added. “Mainly it’s technique.” Iupati will get a chance at redemption against the Chargers when they return to Levi’s Stadium on Dec. 20. Overlooked through much of the offseason is how Iupati has overcome from a lower-leg fracture in last season’s NFC Chmampionship loss at Seattle. He did not need offseason surgery on that left leg, he’s been a full participant in practices and he said it’s improving daily. “It’ll be fine,” Iupati said of his health. “We’ve got one more week (until the regular season).” Lining up to Iupati’s right is a new center in Daniel Kilgore, who’s entering his fourth season but has no career starts. Iupati praised Kilgore’s intelligence and his ability to play low. Kilgore definitely has secured that starting spot, a vacancy created by Jonathan Goodwin’s free agency return to the New Orleans Saints. Rookie Marcus Martin trailed Kilgore in that competition because of an ankle injury entering training camp, then Martin sustained a left-knee injury Sunday that could keep him out the next two months. Coach Jim Harbaugh praised Kilgore’s transition to the first-string role, adding that he has an ongoing streak of avoiding a bad snap. “That’s the last thing I want on my plate, a bad snap,” Kilgore said. “I want to make sure Colin has a good grip on it.” Kilgore notes that he’s ready for the starting role after serving the past three years as Goodwin’s understudy. “The stats show I have not started, but I’ve been with the guys four years and I feel comfortable with it,” Kilgore said. Much of the offensive line’s focus the past five months has been at right guard, where Joe Looney has taken first-team reps while Alex Boone remains entrenched in a contract holdout. A source indicated Monday that Boone and the 49ers remain in a stalemate. Kilgore and Looney are familiar neighbors on the line. They lined up next to each other in reserve roles since 2012, and Kilgore says that enhanced their chemistry together.

Levi’s Stadium’s sod, which was installed on Friday, didn’t take long to make an impact. LaMichael James said he tweaked his ankle on the opening kickoff when his foot slipped on the sod, which was installed Friday. James remained in the game, had seven carries for 9 yards, and an 11-yard kickoff return. Harbaugh said James’ carries went “too wide” at times. Rather than blame the sod, James said he should have worn better cleats. His footing didn’t give way, however, when he nicely executed a couple pass-protection blocks. “I’m proving to y’all I can pass protect,” James said. “Everyone doubts me and I take it personal.” Blaine Gabbert took notice:  “He did a tremendous job. And there were a couple times he’s 1-on-1 with the linebacker and the linebacker’s blitzing the A-gap and he stepped right up, cut him down a couple times and stuck some D-linemen on some pass pro, too.” -- James did not like the grass but others tempered their impressions. “It was a lot improved from Wednesday," McDonald said. "Of course, all the guys were worried going out, but they did a great job preparing for today and it held up really nice.” Added fullback Bruce Miller: “It held up fine. I couldn’t even really tell the difference. Maybe it’s because I’m not moving as fast as some of those other guys. But I just play on it. It felt the same to me and it was holding up good.” -- Harbaugh did not approve of Quinton Patton’s emphatic celebration after his first catch of the exhibition season, a 10-yard conversion in which he had his helmet dislodged by a defender. “We don’t want to see that,” Harbaugh said of Patton’s demonstrative strut toward the crowd. “I talked to him about that.” -- Although several players slept through Sunday morning’s earthquake, James did not, stating: “I thought I was dreaming. I woke up in my bed, hugged it tight and went back to sleep.” Linebackers coach Jim Leavitt felt the earthquake in his family’s Los Gatos home, which their landlord put on earthquake-resistant rollers after it got leveled in the 1989 Loma Prieta quake. Chargers quarterback Philip Rivers felt it: “I looked outside to make sure the whole city wasn’t falling down first, before the Marriott did. There was a little swaying going on for sure.” -- The 49ers' starting defensive linemen each made their exhibition debuts: Justin Smith, Ray McDonald and Ian Williams. “It was a good start right there," Smith said. "I’m thinking about Dallas and I think most guys in here are. So, good tune-up and we’re ready to go.” -- Jimmie Ward, this season’s first-round draft pick, intercepted a third-quarter pass. He had a potential touchdown return of a fumble nullified when officials ruled it an incompletion and upheld that call after a replay challenge. -- The 49ers’ defense started its probable Week 1 lineup, with the exception of strong safety Antoine Bethea (concussion). Bethea’s replacement, Craig Dahl, gave up a touchdown pass to a tight end for the second straight week, this time to Antonio Gates to put the 49ers behind 7-0. -- Gabbert, who entered with NFL's 112th-ranked passer rating of 17.9, posted a 110.4 rating (7-of-11, 66 yards, touchdown, no sacks). -- Michael Crabtree’s first catch of the exhibition season came on a 10-yard strike Kaepernick threaded between two defenders on a second-quarter field-goal drive. -- Adam Snyder saw time at both right and left guard with the first-string unit. Jonathan Martin again started in place of right tackle Anthony Davis, who worked out before the game and isn’t expected to play until Week 1 because of a shoulder injury. -- Special-teams ace Bubba Ventrone (hamstring) and fullback Will Tukuafu (concussion) did not return from their injuries. - Chris Culliver made two solid plays in a three-snap sequence, batting away a deep pass and making a sideline tackle -- The 49ers defense allowed no points on its opening series for the first time this preseason. Eric Reid made a third-down tackle a yard short of the first-down marker. -- Rookie Aaron Lynch (sack, two passes defended, three tackles) credited his play to a new appreciation for practice. “I’ve been working in practice on good habits and getting in better shape,” said the fifth-round pick. “To me, it is different now. In college you don’t have to go hard every play, but those that do have success. It’s one thing I had to learn going into this.” -- Rookie linebacker Chris Borland produced a third-down sack on the second half’s opening series. -- Darryl Morris made a diving interception with 1:49 remaining, aided by Shayne Skov’s coverage on the pass. -- Phil Dawson made both his field-goal attempts Sunday after missing two last week. “I didn’t have enough room in my brain to worry about the field,” Dawson said. “But, every Sunday, or every game day has its challenges competing for your focus and you just got to zero in on what you got to do that day. We handled the (new-field) situation well as a team today.” Dawson said he wasn’t seriously hurt making a second-quarter, point-after kick. -- The Chargers lost center Nick Hardwick (neck) and defensive lineman Kwame Geathers (knee) to second-quarter injuries.