SAN FRANCISCO -- Yes, tonight's Vikings-49ers game is the third preseason contest, which typically is the only one NFL teams treat anywhere close to a regular-season contest. At least into the early part of the third quarter.

Yes, the Vikings and 49ers have done some game-planning and actual individual film study, which NFL teams never do in their first two preseason games. (And, as we all know, the fourth preseason game is a glorified workout for rookies, members of the bottom third of the roster and Vikings fans who haven't realized that The Wave went out of style in the 1980s.)

But if you're expecting the two faces of these franchises to do much more than stand around for tonight's nationally-televised game, well, you'll most likely be disappointed. The Vikings will play reigning league MVP Adrian Peterson, but look for him to be pulled after a series or two and maybe two or three carries.

Meanwhile, the 49ers also have been extremely cautious with quarterback Colin Kaepernick. Not only has Kaepernick established himself as a Super Bowl-worthy QB, the 49ers also have little confidence in their backup QBs. They now have four of them after signing Seneca Wallace this past week.

In two preseason games, Kaepernick has played only two series, attempted six passes and run only one time for 6 yards. Kaepernick went 4 of 4 for 38 yards and ran that one time while leading a 13-play, 62-yard field goal drive in the 49ers' 10-6 preseason-opening loss to Denver. Kaepernick then completed 1 of 2 passes for minus-3 yards in the opening drive of a 15-13 win at Kansas City. The 49ers kicked a field goal on that drive as well because of Frank Gore's 52-yard run. Gore, by the way, has only two preseason carries, so don't expect to see a lot of him, either.

Defensively, the 49ers are expected to start rookie Eric Reid, the 18th overall draft pick, at free safety. The rook said he's excited about facing Peterson.

"I'm looking forward to it," Reid said via 49ers.com. "That's obviously a guy I've watched a lot growing up. So that'd be nice. Maybe if I can tackle him, get a solo tackle and have a picture, that's be something I would keep."

A solo tackle on Peterson by a rookie free safety? Yes, that would indeed be something.

We'll be back shortly before kickoff with another look at tonight's preseason game at Candlestick.