The San Francisco 49ers have two credible candidates to be named NFL MVP in Brock Purdy and Christian McCaffrey, says head coach Kyle Shanahan, though he can't split them.

The Niners are the only team in the NFL to have booked their playoff spot ahead of the Week 14 games, and they are also in pole position for the NFC's top seed after reeling off five straight wins.

Purdy has enjoyed a breakout campaign in his first full season as San Francisco's starting quarterback, with only the Miami Dolphins' Tua Tagovailoa (3,697) and Houston Texans' C.J. Stroud (3,631) bettering his 3,553 passing yards this year.

He – alongside Dak Prescott and Lamar Jackson – is among the favourites to win the league's top individual prize, though Shanahan believes McCaffrey should also be in contention.

McCaffrey leads the league with 1,177 rushing yards this season, and Shanahan does not see why he couldn't become the first non-quarterback to be named MVP since Minnesota Vikings running back Adrian Peterson in 2012.

"Are you trying to get me in trouble with those two guys?" Shanahan said on Thursday when asked who he would vote for. 

"That's the only reason I wouldn't overly comment on either one of them, because I don't want them to cancel each other out."

Miami's electrifying wide receiver Tyreek Hill is among the non-quarterbacks tipped to be in contention, but Shanahan feels McCaffrey has the strongest case outside the signal callers.

"If any non-quarterback's going to get MVP, I don't get how Christian McCaffrey can't," Shanahan said. "I mean, he's been amazing in what he has done all year.

"If it's going to a quarterback, then I don't have to talk about Christian, I can talk about our quarterback.

"If his numbers are all you see, then I think that solves it. But if you watch the film, then it makes it even stronger, which to me is the most important thing."

The 49ers take on the Arizona Cardinals in their penultimate road game of the regular season on Sunday before facing the Baltimore Ravens – currently the AFC leaders – in a huge clash on Christmas Day.