With three weeks before the Vikings' first playoff game at U.S. Bank Stadium in five years, coach Kevin O'Connell said his team is still "on the hunt" for improvement as well as playoff seeding. Getting better quickly is a particular focus for the NFL's last-ranked defense, which still resides in Minnesota even after the Vikings held the Colts offense to a stingy 4.3 yards per play (tying their season best).

Veteran cornerback Patrick Peterson, who has waited seven seasons since his last playoff game with Arizona, knows the Vikings have a rare opportunity ahead. He doesn't want that spoiled because of some growing pains in first-year coordinator Ed Donatell's system.

Peterson credited Donatell, the 65-year-old play caller, for being flexible in Saturday's 39-36 overtime victory over the Colts. The Vikings bombarded Indianapolis quarterback Matt Ryan with second-half blitzes and more aggressive coverage to help fuel the historic comeback.

"It's a learning curve, because if you think about it, it is all our first year together," Peterson said Wednesday. "Obviously, Coach Ed has a scheme that he feels is best for the team, but you also want to put your personnel in the best position possible. I think that's what now happened."

"Fourteen games in," he added, "having a lot of game film on tape, understanding how teams are attacking us, and trying to put us in better situations so we can be much more successful in this stretch."

Donatell pointed to the Vikings shutting down deep throws as the biggest change following a franchise-worst streak of five consecutive 400-yard games allowed. The Colts attempted only three throws at least 20 yards downfield. All three fell incomplete, according to Pro Football Focus. Both players and coaches fared better, Donatell said.

"It's a combination," he said. "We're going to position our guys to whatever we think the best position is. We're still learning them. I can tell you there's been different combinations: young players, new players. It's our job as a staff to figure that out."

One lineup change that could stick is cornerback Duke Shelley, the 26-year-old journeyman who has started two games. Against the Colts, he replaced third-year cornerback Cameron Dantzler, who was sidelined by an illness. Dantzler is listed questionable to play Saturday against the New York Giants after his ankle injury continued to limit him during practices this week. He has surrendered a handful of big plays and touchdowns — including two scores in a loss to the Lions two weeks ago — due to miscommunication in Donatell's zone-heavy defense.

O'Connell said Thursday the team hadn't decided on a starter yet.

"You can't measure what's inside of that guy," Donatell said of Shelley. "You see him come up big in moments for this team and his contributions will be needed down the line."

Slot cornerback Chandon Sullivan gave Shelley, who deflected two passes against the Colts and had a key third-down tackle, unprompted praise when asked about the defensive adjustments.

"We're trying to get more aggressive," Sullivan said. "We want the rushers to rush and the back end to cover and make plays. That's what we've been able to do, especially with guys like Duke."

Peterson said he was thankful for the "opportunity to be aggressive" in last week's game plan, which allowed him to play more press coverage to disrupt the timing of routes.

But players reiterated that the Vikings' defensive foundation remains three-deep zone coverages aimed at keeping eyes on the quarterback and breaking on the ball. Linebacker Jordan Hicks said they can bring an aggressive mentality to any defensive play call.

They can also throw a curveball or changeup now, too.

"You see it all around the league. That's our bread and butter," Hicks said. "But when teams are expecting that, you change up on them on a second down: bringing pressure and man [coverage] on the back end. It's keeping them off balance."

The Vikings pass rush also reignited against the Colts. Edge rusher Danielle Hunter had a season-high four quarterback hits, including 1½ sacks. Hicks, safety Harrison Smith and linebacker Eric Kendricks frequently blitzed.

But Saturday's foe, the Giants, will know all three of those defenders well.

Andre Patterson, the former Vikings defensive coordinator and D-line coach, is now coaching the Giants defensive line. He has been an asset for the Giants offense this week.

"Dre has been helpful where he can," Giants offensive coordinator Mike Kafka told New York reporters. "We pick the brains of all of our coaches."

Peterson elevated Saturday to a "playoff game" feel. The Giants are fighting for a postseason berth and could return to Minnesota next month in the NFC wild-card round against what Peterson hopes is a surging defense after last week's showing.

"We have to continue to build on that and see where it takes us," Peterson said.