As the seconds wound down in Monday’s opening round of aero kit testing at Barber Motorsports Park, Team Penske was un-rivaled — Simon Pagenaud, Will Power, Juan Montoya and Helio Castroneves sitting first through fourth on the timing chart.

But on the very last lap of a seven-hour practice period Scott Dixon pipped the Penske boys to claim the fastest lap.

“I had to do it, grinned Dixon after turning a best of 1:07.480 in the Target Dallara/Chevy. “We weren’t going to put on tires but then we decided we couldn’t let those guys sweep us.”

The spirited competition between the teams of Chip Ganassi and Roger Penske is nothing new for the Verizon IndyCar Series and, as Dixon proclaimed, “It’s just a test and I don’t get too excited about who’s going fast until we get to St. Pete (series opener on March 29). But it’s a good start.”

Especially for the General Motors teams as they claimed seven of the top 10 times. Pagenaud, the fourth bullet in The Captain’s high-powered attack, paced the morning session and came back second best in the afternoon with a lap of 1:07.532 in the Penske Truck Leasing Dallara/Chevy.

Defending IndyCar champ Power checked in at 1:07.549 in the Verizon car while Montoya ran 1:07.626 and Castroneves 1:07.770. It’s the debut of the aero kits, which are easy to distinguish from each manufacturer and drawing early rave reviews from the GM drivers.

“Man is it fast! I’m almost wide open running into Turn 1,” said Power. “I think right now Chevy has the advantage and I expect them to because they’ve done a lot of good work.”

Ryan Hunter-Reay was the fastest of the Honda drivers and only four-tenths of a second behind Dixon.

“I’m not close to running flat out in Turn 1 and we’re still trying to find the balance because nothing from the past here is relevant with these new kits,” said the 2014 Indy 500 winner.

Twenty of the 21 cars posting times sported the new aero kits, only Francesco Dracone in Dale Coyne’s second car running with last year’s Dallara.

While it was a fast session for most of the Chevrolet-powered teams, it was a short one for rookie Sage Karam. Driving the fourth car of Chip Ganassi’s armada, Karam lost control in Turn 14 during his third lap and pounded the guardrail.

“It’s a flat out right-hander and my car bottomed out, I corrected it and it went straight left,” explained Karam, whose right hand and wrist were wrenched in the accident that cracked the tub of his GE LED Dallara/Chevrolet. “I feel bad for my guys but we’ll be alright. I should be good to go for a test in New Orleans next week.”

The 2013 Indy Lights champion had been nothing but impressive during earlier tests for Ganassi and Dario Franchitti figures it was just a typical mistake for a rookie.

“The tire temps probably weren’t up yet so he bottomed out and it got away. It happens to all of us,” said the three-time Indy 500 winner who is serving as Karam’s coach in 2015.