If it seemed as if the Vikings might never finish off Sunday's 24-13 upset of San Francisco, that's exactly how coach Leslie Frazier and his staff felt on the sidelines.

In what has become a leaguewide trend in the year of the replacement official, the end of Sunday's contest was muddled with confusion and a mind-boggling misinterpretation of the rules.

The chaos began with 3 minutes, 29 seconds remaining. With the Vikings up 11 and trying to run time off the clock, running back Toby Gerhart took a handoff and was stopped for what appeared to be no gain.

San Francisco immediately called its third and final timeout. Yet during the timeout, 49ers coach Jim Harbaugh asked the officials for a challenge, asserting Gerhart had fumbled on the previous run.

A team is not allowed to challenge a play without any timeouts left, San Francisco was granted its request and refs ruled Gerhart lost his fumble, which was recovered by 49ers linebacker Patrick Willis.

Compounding the confusion, on the Vikings' next possession, Gerhart was again stopped for what was ruled on the field to be a 2-yard gain. Yet without a timeout or a challenge left, Harbaugh was again allowed to use both, first calling a timeout with 2:18 left and then again asking for a challenge on a Gerhart fumble.

Officials granted both, but then determined on replay review that Gerhart had recovered his own fumble.

Following the game, a pool reporter asked referee Ken Roan for an explanation.

"[Harbaugh] called a timeout immediately after the play was over," Roan said. "Then realizing that, 'Hey this is something that I want to challenge, but I just used my last timeout, can I challenge and get my timeout back? How does that work?' He asked the guys on the side and they came over and got me. What I told him was, 'Well, you challenged it not knowing what the result of the play was going to be.' So I granted him the challenge, and we went and looked at it.

"That was wrong. I should not have."

Frazier tried to get clarification during the chaos but wound up as confused as everybody else.

"We'll have to get some clarification on Monday," he said. "There were some head-scratchers. There was no question about it. ... I'd mess it up to try to explain it to you."

Raymond suffers serious ankle injury

The Vikings absorbed their most significant injury to date on the final play of the first quarter when starting safety Mistral Raymond hurt his right ankle while trying to tackle 49ers running back Frank Gore. Raymond's ankle bent awkwardly as he tried to plant. He fell to the turf, writhing in pain and was immediately put in an air cast and carted off the field.

"From the naked eye, it looks like a very serious injury," Frazier said. "But I don't know all the details [yet]."

Block party

Give Vikings defensive tackle Letroy Guion credit not only for blocking a 43-yard David Akers field-goal attempt late in the first half but for also delivering a Usain Bolt-like celebration sprint immediately after he felt the football hit his palm.

"That's like the best feeling in the world," Guion joked. "I was pumped up, man. Full of adrenaline. That was a great moment for me."

Guion's block, with an assist from Matt Kalil, came with 52 seconds left before halftime and the Vikings ahead 14-3.

"The key there is ball, get off," Guion said. "Get two steps up the field and get your hands up. That's what the coaches teach us. Me and Kalil got a great jump. We got them back a little bit, got our hands up and took away those three points."

The offense quickly capitalized, putting together a nine-play, 33-yard drive that ended with Blair Walsh's 52-yard field goal as the half ended. Walsh's kick marked the third consecutive game in which he made a field goal from longer than 50 yards, a Vikings record.

Dodging a bullet

Gerhart wasn't the only running back to have ball security woes Sunday. Adrian Peterson (25 carries, 86 yards) dropped an easy short pass from Christian Ponder midway through the third quarter. Then, on the next play, Peterson fumbled at the end of a 5-yard run. That error could have been disastrous, coming shortly after San Francisco had closed to within 17-13. But Peterson's fumble was recovered 4 yards up the field by Percy Harvin. And the 49ers also incurred a 15-yard unnecessary-roughness penalty on the play. So instead of a momentum-changing turnover, the Vikings ended up netting 24 yards.

Upping the load

Against a stingy San Francisco run defense, Peterson never could get much going. His longest run was a superb 20-yard spurt in the fourth quarter. But 16 of Peterson's other 24 carries went for 3 yards or less.

Still, a 25-carry effort is further proof that the Vikings coaches are letting Peterson take on a heavy workload.

Said Frazier: "He had mentioned to me during the week, 'Coach, you don't have to limit me anymore. I'm ready. Feed me.'"

Frazier did turn things over to Gerhart down the stretch, admitting he was conscious of Peterson's workload.