NFL Preseason Preview - San Diego (2-0) at Minnesota (1-1) (ET)

(Sports Network) - The San Diego Chargers and Minnesota Vikings will be ratcheting up the intensity when the teams face off at the Metrodome for an important preseason test, though both participants will be continuing to make do without the services of their best running back for Friday's game.

Though the comeback of Vikings standout Adrian Peterson from a potentially devastating knee injury the four-time All-Pro suffered in late December of last season remains right on schedule, the team announced its intention to hold out the powerful back for the remainder of the preseason as a precaution. Peterson just resumed practicing on Aug. 14 and has still yet to be cleared for taking part in contact drills.

Peterson is still expected to be ready when Minnesota opens its regular season against Jacksonville on Sept. 9.

"There are no setbacks, that's not the reason we're doing it," said Vikings head coach Leslie Frazier when informing the media of the decision on Tuesday. "We just feel like more time with him in practice with some of the things we're doing and the progression of getting him ready for the season is the right thing to do."

The Vikings got by just fine without Peterson last week, amassing 160 rushing yards as a team en route to a 36-14 victory over visiting Buffalo. Toby Gerhart had 30 yards on six carries while serving as the first-string tailback in Peterson's absence, with fleet-footed quarterback Joe Webb racking up a game-high 64 yards on a pair of scrambles.

Starting signal-caller Christian Ponder did his damage with his arm in Friday's victory, with the 2011 first-round pick completing 10-of-13 passes for 136 yards and a touchdown before giving way to Webb in the second quarter. Rookie linebacker Audie Cole was Minnesota's defensive star, picking off a pair of passes and returning both for touchdowns within a 13-second span late in the game.

Cornerback Chris Cook did sustain a concussion against the Bills and will be held out of Friday's tilt as a result, while defensive tackle Letroy Guion and tight end John Carlson will miss another week for the Vikings as both recover from knee sprains.

The Chargers are bracing for an absence from 2011 leading rusher Ryan Mathews that could extend into the early stages of the regular season. The injury- prone third-year back fractured his collarbone on his first carry of San Diego's preseason-opening win over Green Bay on Aug. 9 and is facing a 4-to-6 week timetable to return, putting his status for Week 1 in question.

Veterans Ronnie Brown and Jackie Battle and holdover Curtis Brinkley will work in a timeshare while Mathews heals, though none of them were effective in Saturday's matchup with Dallas. The trio combined for a meager 30 rushing yards on 14 attempts.

Quarterback Philip Rivers hit on a sharp 13-of-15 throws for 109 yards against the Cowboys, but was intercepted twice in San Diego's 28-20 triumph in which backup Charlie Whitehurst delivered a pair of touchdown passes to rally the Bolts back from a 10-0 halftime deficit.

Whitehurst's first score was an 18-yard strike to Vincent Brown, but the second-year receiver fractured his ankle on the play and will be sidelined for at least the next two months.

The Chargers are already operating with a somewhat depleted receiving corps, with slot man Eddie Royal having missed the first two games with a groin injury that may keep him out of this contest as well.

Nose tackle Antonio Garay is likely to sit out another week for San Diego due to a sprained ankle, while center Nick Hardwick is doubtful to suit up after suffering a concussion in Tuesday's practice.

These teams opposed one another in San Diego in the 2011 regular-season opener, a 24-17 Chargers' win, but haven't locked horns in preseason play since 2005. The Vikings took that encounter by a 19-16 count to grab a 10-2-1 advantage in the overall series.