ANDERSON, Ind. — It took just a little time for Andrew Luck to win over the most skeptical of Indianapolis Colts fans last season, with the rookie quarterback’s ovation growing louder each time his name was announced at Lucas Oil Stadium.

By season’s end Luck had thrown for a rookie-record 4,374 yards, led seven game-winning drives and helped the Colts to a suprising 11-5 record and wild-card playoff berth. That was enough to earn him the runner-up spot in the Rookie of the Year race against Washington Redskins quarterback Robert Griffin III and erase most doubts about his ability to lead the franchise formerly helmed by Peyton Manning.

As NFL free agency opens today, protecting the new face of the franchise figures to be Indianapolis general manager Ryan Grigson’s No. 1 goal.

“The last guy in the last seat in the stadium can see that (No.) 12’s pretty good,” Grigson said during last month’s NFL Scouting Combine. “You want to take care of him, set the table for him, make sure that he’s comfortable. But you also want to have the best team year-in, year-out possible. You want to have balance.”

Luck was sacked 41 times last season, and many of the early indicators suggest the Colts will attempt to strengthen an offensive line primarily pieced together out of spare parts a year ago.

The NFL allowed teams to begin contacting agents for potential targets on Saturday, and Indianapolis reportedly has shown interest in the top two available offensive guards — 26-year-old Andy Levitre of the Buffalo Bills and 25-year-old Louis Vasquez of the San Diego Chargers.

The Chicago Bears, Tennessee Titans and Bills also are expected to be extremely active on the offensive linemen market. Vasquez might be the better fit for the Colts because of new vice president of football operations Jimmy Raye, who was part of the front office in San Diego that drafted Vasquez in the third round out of Texas Tech in 2009.

Indianapolis also could pursue one out of a deep class of offensive tackles that includes former Miami Dolphins No. 1 pick Jake Long, Cincinnati Bengals first-rounder Andre Smith, New Orleans Saints Pro Bowler Jermon Bushrod and recently released Pro Bowler Eric Winston of the Kansas City Chiefs.

With that position also deep in April’s draft, Grigson can afford to be patient and look for the best value.

“We’re not going to do anything fiscally unresponsible because I don’t want to end up being in cap straits,” the GM, who opened the offseason with an estimated $43 million in salary cap room, said last month. “That can really hamstring you. We’ll be smart how we approach it. We’re going to build this thing smart. We’re going to build this thing the right way.”

On the defensive side of the ball, the immediate focus is likely to be on pass rushers. Reports again have linked the team to the top free agent targets — Baltimore Ravens outside linebacker Paul Kruger and Detroit Lions defensive end Cliff Avril.

The Cleveland Browns also have shown great interest in Kruger, and a bidding war could erupt for his services. Avril played last season under the franchise tag and has spent his five NFL seasons in a 4-3 scheme. He played outside linebacker at Purdue, however, and has told Detroit media he is open to switching into a 3-4 scheme like the one run by the Colts.

The Colts also could look to add talent in the defensive secondary.

Indianapolis has been working to re-sign cornerback Jerraud Powers, but they might not be willing to match what he could get on the open market. Nickelback Darius Butler also is in negotiations to return but will become a free agent at 4 p.m. if a deal is not reached.

Among the available players the Colts could target as replacements are Baltimore’s Carey Williams — a reported favorite of Indianapolis head coach Chuck Pagano during his four seasons on the Ravens’ coaching staff — and San Diego’s Antoine Cason — another player with ties to Raye.

There also is rumored interest in veteran Ravens safety Ed Reed, who recently signed with Athletes First — the agency that represents Colts receiver Reggie Wayne, Reed’s former roommate at the University of Miami.

Despite the flurry of reported interest, Pagano said last month he doesn’t see many glaring holes in the Indianapolis defense.

“I don’t think we’re that far away,” he said. “You get those two guys healthy (nose tackles Josh Chapman and Brandon McKinney) and find a couple of other pieces to the puzzle in the front seven, a backer here, a backer there, I think we’re close.”

One of the more intriguing names cropping up on the rumor mill late Monday evening was Green Bay Packers wide receiver Greg Jennings. Indianapolis’ own Donnie Avery is a pending free agent, and the Colts could look to upgrade Luck’s weapons cache.

Even with the high amount of cap space available, however, Jennings might prove to be too rich an addition.

One thing appears certain as the market plays out over the next few weeks. After his first season was limited by the need to purge an aging roster and the handicap of shrinking cap space, Grigson will be aggressive this spring in his pursuit of players he believes can help the Colts win.

“Last year I was in a completely different situation,” Grigson said at the combine. “It’s nice to be able to go shopping a little bit. It’s nice to be able to know that if there is someone I’m really pining for, I’ve at least got a crack at him.”