Vikings tackle Mike Harris was caught off guard last week against the Packers.

He was told to enter the game.

Backups will always deliver the you-never-know-when-your-number-will-be-called cliché throughout a season, up until the moment they are instructed to strap on a helmet. That was the case once right tackle Phil Loadholt tore his pectoral muscle in the fourth quarter.

"As a backup, it's a little stressful. But you can't miss a beat once you get in," Harris said.

Harris played nine snaps, but with Loadholt placed on injured reserve this week, Harris will start against the Carolina Panthers on Sunday.

"I just know anything can happen," Harris said. "This week I was thrown in, the 13th week of the season, and I'm getting my first start [this season]. … I'm excited; I know how fun it is. I know what I got to do on Sunday and that's kick butt. I can't wait."

Harris will make his 13th career start, and first with the Vikings, in his third season out of UCLA. He started at times with the Chargers during his first two seasons, and spent his rookie year under Vikings offensive coordinator Norv Turner, San Diego's head coach at the time. Harris was placed on injured reserve last season because of an ankle injury after starting three of the first five games.

"I've been here," Harris said. "I know what it takes to win. It takes total focus, preparation and tenacity, too."

Without Loadholt at right tackle, the Vikings will miss a critical part of their run game. He was one of their best run blockers with right guard Brandon Fusco, who is also on injured reserve because of a torn pectoral.

"The main thing for [Harris] is just making sure he's preparing himself mentally for the game plan and getting ready for [defensive end] Charles Johnson, who is a great rusher in this league," Loadholt said. "Mike will have his mind right and getting ready to go."

Johnson's sack numbers haven't been on par with his previous two seasons, 12½ in 2012 and 11 last year, but it will still be a challenge for Harris. Johnson has five sacks this season on a defensive line hampered by Greg Hardy's absence. He has been on the commissioner's exempt list because of charges of assault of a female and communicating threats in May.

But facing defensive ends Everson Griffen and Brian Robison in practice should help Harris, Fusco said.

"Two of the best in the league," Fusco said. "He's not going to see anyone better than that I feel like, so he's ready for anything that's thrown at him."

Harris will at least start against the Panthers. From there, it'll likely depend on his performance whether Harris will get trumped by newly acquired tackle J'Marcus Webb or rookie offensive lineman Austin Wentworth. Once Fusco was placed on injured reserve, Vladimir Ducasse started four games, then was replaced by Joe Berger over the past four games.

This will be a big opportunity for Harris not just to remain as the Vikings starter for the final five games this season but to advertise his ability leaguewide. He will be an unrestricted free agent in the offseason.

"This is his opportunity to shine and show teams, not just even the Vikings, but show other teams what he can do," Fusco said. "I'm sure he'll do great, and he's going to go out there, work as hard as he can and be a great right tackle."