Stephen Perofeta on the key to the Blues win over the Crusaders

The Blues 26-6 win over the Crusaders was a resounding defensive effort, holding the defending champions try-less for the first time since 2015.

Winger Caleb Clarke can be thanked in part for that after a miraculous cover tackle on centre Levi Aumua in the second half, dislodging the ball as Aumua dived over to score.

First five-eighth Stephen Perofeta said the key for the Blues beating the Crusaders was "keeping it simple" as they relied on physicality to bulldoze the Crusaders anytime they reached the 22.

"In fairness it is a great outcome, but we just wanted to make it real simple this week," Perofeta told Sky Sport NZ.

"The Crusaders have dominated that physical battle, the set-piece battle, every year they have been successful.

"They are still that team, it's still early in the season, but for our boys we are proud that we put on a performance that we talked about the whole week."

The first half played out with the home side taking a 9-6 half-time lead before a 20 minute period of Blues power rugby overwhelmed the Crusaders to start the second half.

Prop Ofa Tu'ungafasi scored the first try after a relentless barrage of forward carries, which was followed up by a quick strike to centre AJ Lam to extend the lead to 23-6.

The Blues camped inside the Crusaders' 22 soon after and continued to pile on the pressure through the big men.

Perofeta said that there weren't any special half-time talks to attribute to one of their best periods of rugby this season.

"Nothing new [was said], we just talked about keeping it simple around the way we exit and the way we kicked," he said.

"And just our basics, we made a few errors in the first half around handling errors, and we still made them in the second half.

"We just tried to make it simple around trusting our defence, taking care of the pill."

On whether keeping the Crusaders try-less indicated that something different was brewing this season, Perofeta said so.

"Yes, we are fighting for every moment, Caleb's a player who will just keep doing that, right to the 80th [minute]," he said of Clarke's effort.

"It's round five, we are building nicely against a quality Crusaders time, to keep them tryless is great from our defence."