SANTA CLARA, Calif. - The San Francisco 49ers outlasted the Denver Broncos, winning a defensive struggle 24-14 at Levi's Stadium on Sunday. The 49ers stayed undefeated, moving to 4-0, while the Broncos fell to 2-2. A 3-3 deadlock was snapped in the third quarter after Siran Neal forced a fumble on a punt return by Marvin Mims Jr. and recovered it at the Broncos' 28-yard line to set up a 49ers touchdown for their first lead of the day. The short drive, culminating with a 1-yard touchdown pass from Brock Purdy to Deebo Samuel, marked only the second time the 49ers reached the red zone. The Broncos' defense remained stout despite losing All-Pro cornerback Pat Surtain II in the second quarter and fellow starting cornerback Riley Moss to start the third quarter, keeping Purdy and the 49ers offense, which ranked second in scoring and fifth in yards coming into the week, in check most of the day. But a nine-play, 73-yard drive, capped by a 1-yard Christian McCaffrey touchdown run, moved the lead to 17-6 in the fourth quarter. The Broncos wouldn't go away, driving 70 yards on eight plays, capped by a 13-yard Bo Nix TD pass to Jaylen Waddle. Tyler Badie tacked on a two-point conversion to pull within three with 4:05 left in the fourth. Another Broncos comeback wasn't in the cards, though, after George Kittle took a short pass from Purdy 56 yards for a touchdown to ice the game. The 49ers will look for a third NFC West win when they travel to play the Seattle Seahawks next week. The Broncos will visit the Chargers. How impactful was Siran Neal's special teams play? The MVP of Sunday's game? One candidate certainly is Neal, the gunner who forced a punt-return fumble that broke open the game. Tied 3-3 midway through the third quarter, the 49ers had been pinned deep in their own territory when Corliss Waitman crushed a 61-yard punt down the left sideline. That gave Mims a chance to return, but he was immediately hit by Neal and lost the ball - which officials ruled happened before Mims' wrist touched the ground. The Broncos didn't dispute the call after the game, with Mims saying simply that he lost that ball, and, "I can't do that." "We don't have any type of good angle," Broncos coach Sean Payton said. "... That was opposite our bench. Any time there is a turnover, you're going to rely on replay and it really doesn't matter. They just said the review said it was a fumble." Over the past two seasons, the 49ers have emphasized special teams more than ever in the Kyle Shanahan era. Neal and linebacker Luke Gifford are on the roster because of their kick-coverage ability. Neal has served as one of their gunners this season. The other has been a receiver - KhaDarel Hodge and, after Hodge's recent knee injury, Malik Turner - who also specializes in kick coverage. - Matt Barrows, 49ers beat writer How big has Deebo Samuel's impact been since returning to the 49ers? The 49ers couldn't get the running game going, so they turned to Samuel. And after they couldn't find the end zone all day, they threw it to Samuel. On a team that has lost four receivers already this season and had a fifth, Mike Evans, playing with cracked ribs, Samuel helped save the day. Not bad for a guy no other team wanted to sign this offseason, which enabled him to return to the 49ers after Ricky Pearsall needed surgery. Samuel had three rushes for 44 yards and five catches for 26 yards and a touchdown Sunday. And like the previous week when he went 80 yards on a hook-and-lateral play, Samuel showed he still has top-end speed. Being unemployed is a great motivator to get back in top shape. He also came in off the street knowing Shanahan's playbook very well. At 4-0, the 49ers will now try to avenge last year's ugly playoff loss to the Seahawks, and they have an old, familiar lightning rod to help them. - Vic Tafur, 49ers beat writer How will Vance Joseph's defense react to the potentially massive absence of Surtain? Surtain dropped to the Levi's Stadium turf late in the second quarter with no one around him. He grabbed toward his right ankle as trainers quickly surrounded him and later helped the limping All-Pro to the locker room. It was a discouraging sight for a defense that is built around Surtain's ability to lock down an opponent's top target and generally render wide swaths of the field inaccessible to quarterbacks. The Broncos survived a brief Surtain absence last season, winning all three of the games the 2024 NFL Defensive Player of the Year missed in the middle of the year with a pectoral injury. But any extended absence for Surtain would severely alter the way coordinator Vance Joseph can attack opponents. The task became even more difficult in the second half Sunday because the Broncos were also without Moss. The starting cornerback opposite Surtain didn't play in the second half because of a ribs injury. That left Jahdae Barron and Kris Abrams-Draine on the outside, and Purdy began finding spots to attack both young players during a pair of second-half touchdown drives that flipped the game. Payton said after the game he did not know the severity of any of his team's injuries, including another that sent receiver Pat Bryant off the field on a cart, but acknowledged that Surtain and Moss' absences impacted the Denver defense. "It's very difficult. Pat is definitely a key part of our team," Broncos receiver Jaylen Waddle said of Surtain. "I told him to keep his head up and we're all praying for him." The Broncos' defense played well, even though it couldn't become the first unit to sack Purdy this season. The Broncos believe in the depth they have added in the draft over the past three seasons. But any team that loses its best player will have an uphill battle to replace him, and that will certainly be true for the Broncos if they are forced to play an extended period without Surtain. - Nick Kosmider, Broncos beat writer The Broncos had an average distance to gain on second down of 9.2 yards in the first half Sunday. The culprit of those disadvantageous down-and-distance scenarios was a running game that simply hasn't been good enough. J.K. Dobbins, who was the NFL's fifth-leading rusher at the time of his Week 10 foot injury last season, hasn't looked like the same player since re-signing with the Broncos on a two-year deal that came with $8 million in guarantees. He had only 40 yards on 11 carries Sunday, and a good chunk came on a drive late in the fourth quarter. Rookie Jonah Coleman is on injured reserve and is eligible to return in Week 7. The Broncos may be ready to give him a long look as a leading rusher if there is no meaningful improvement in the run game beginning with next week's road game against the Los Angeles Chargers. The Broncos found themselves chasing once again in the fourth quarter because their offense wasn't sustainable enough to produce consistent scoring opportunities. Payton and others made clear heading into Sunday's game that avoiding another late-game chase would come down to running the ball more efficiently on early downs. That was a big swing and miss in the Bay Area. - Kosmider What did it mean for the 49ers to have Mike Evans and Fred Warner gut it out? It was clear that Evans, dealing with a broken rib, was both on a pitch count and in pain Sunday. After one catch in the second quarter, the 49ers receiver doubled over, came off the field and paced the sideline for a bit. Evans declined to don a flak jacket for the game - he thought it made him look weak - and instead said he'd wear a compression jersey with built-in padding. He ended up leading the team in targets (8) and receiving yards (76). Evans was one of two San Francisco headliners playing in discomfort. Linebacker Fred Warner went to the medical tent early in the game and was slow to get up after a couple of plays. He went into the locker room before the first half ended and was the last player to come out for the second half. Niners coach Kyle Shanahan said after the game that Warner had been dealing with stomach issues, but he didn't miss any defensive snaps. - Barrows