49ers @ Vikings Game Overview

But the calf injury and Achilles tendinitis that caused him to sit out the 49ers' season opener continues to flare up, and McCaffrey will sit out again in Week 2.

In fact, he might be placed on injured reserve after a setback in Thursday's practice.

The developments of the week are much different than McCaffrey envisioned. Earlier this week, he said "my mindset is I'm going to play no matter what I'm going through on Wednesday or Thursday in practice."

San Francisco (1-0) will stick with the backup plan, which was a sensational move in the opener. The 49ers turned to second-string running back Jordan Mason on Monday, and he had 28 carries for 147 yards and a touchdown in his NFL debut to lead the team to a 32-19 win over the visiting New York Jets.

Meanwhile, Minnesota (1-0) is looking to play the role of spoiler in its home opener. The Vikings are coming off a decisive 28-6 win over the New York Giants in Week 1 that marked the team debut for Sam Darnold at quarterback.

Darnold completed 19 of 24 passes for 208 yards, two touchdowns and one interception to register a 113.2 passer rating. He now will go up against the 49ers, with whom he played last season as a backup to starter Brock Purdy.

A season on the sidelines was a blessing in disguise, Darnold said.

"Being able to prepare and be ready like I was the starter, but just sit back and watch everything that was going on in the organization, how things were run there, (really helped)," Darnold said. "I really did learn a ton from Brock and the way he prepared, his quiet confidence that he had every single day.

"He's not the rah-rah guy, not going to lead the team in breakdowns at the end of the year, but he's just as steady as they come."

Purdy proved steady last week as he completed 19 of 29 passes for 231 yards. He also had one rush for 11 yards in the victory.

Both teams' defenses will look to repeat impressive performances in Week 2.

San Francisco held the Jets to 266 total yards and spoiled the opener for Aaron Rodgers, who passed for 167 yards, one touchdown and one interception. Leonard Floyd recorded a sack for San Francisco.

The Vikings also shined in defensive coordinator Brian Flores' system. Free-agent acquisition Andrew Van Ginkel had an interception return for a touchdown, and veteran safety Harrison Smith baited Daniel Jones into another interception.

Minnesota racked up five sacks, including a pair from linebacker Patrick Jones II. Van Ginkel also notched a sack, as did rookie edge rusher Dallas Turner.

San Francisco wideout Brandon Aiyuk is hoping for better production in his second game back from a long delay over a contract dispute. Aiyuk caught two passes for 28 yards in Week 1 but said he felt like he was in good game shape.

"It felt good," Aiyuk said. "(I felt) a little sore. (I was) solid though."

Vikings wideout Jordan Addison was ruled out of Sunday's game after he did not take part in practice because of a Week 1 right ankle injury. Addison had three catches for 35 yards before he left the game in the third quarter. Jalen Nailor will start opposite Justin Jefferson.

Safety Harrison Smith (hip), tackle Brian O'Neill (elbow) and guard Ed Ingram (tricep) were limited at practice on Friday and are listed as questionable for the game.

San Francisco listed safety Talanoa Hufanga (knee) as doubtful and linebacker Dee Winters (ankle) as questionable.

--Field Level Media