Helio Castroneves

SONOMA, Calif. – The Verizon IndyCar championship battle rages to its climax this weekend at the GoPro Grand Prix of Sonoma with two Team Penske drivers vying for the title, but it was a third Penske pilot stealing the spotlight on Friday.

Helio Castroneves led both practice sessions in the No. 3 Hitachi Team Penske Chevrolet, posting a lap in the later practice that ranged within half of a second of the Sonoma Raceway track record.

Castroneves ran a fast lap of 1 minute, 16.6678 seconds (111.990 mph) in the 75-minute afternoon session, followed by teammates and remaining championship contenders Will Power (No. 12 Verizon Chevrolet, 1:16.7072) and Simon Pagenaud (No. 22 Hewlett Packard Enterprise Chevrolet, 1:16.9757).

GOPRO GRAND PRIX OF SONOMA: Practice 2 resultsCombined practice results

“I love racing at Sonoma and the Hitachi Chevy was great today,” said Castroneves, winner at Sonoma in 2008. “We had a really good test here last week and that certainly helped today.

“It's good to be on top, but you don't get any points for leading practice. We have to keep pushing to stay on top.”

The track record, set by Power in Verizon P1 Award qualifying last year at 1:16.2597, could be in danger of being beaten in Saturday’s knockout qualifying.

Power, a three-time winner and five-time pole sitter at Sonoma, trails Pagenaud by 43 points for the series championship. With double points available in Sunday’s 85-lap race on the 2.385-mile permanent road course, Power is the only competitor mathematically eligible to beat Pagenaud, who has led the points since the second race of the season.

“Just excited to be here,” said Pagenaud, who has won four races on the year – three on road courses. “Excited to be in this fight, excited that we're able to, with Will and our teammates, bring another championship for Team Penske in the 50th year anniversary of the team.”

Team Penske will claim its 14th Indy car championship Sunday. Over its 50 years, the team has accrued 186 Indy car wins, including nine this season.

Pagenaud and Power vowed to fight hard for the title of Verizon IndyCar Series champion.

“We need to get this championship for the team,” said Power, who captured Team Penske’s last championship in 2014. “We know we've got it now, it's between Simon and I. … We have a realistic shot this weekend (to beat Pagenaud). Everything's got to fall into place.”

“At the end of the day it's about doing the best you can,” said Pagenaud, vying for his first title. “And doing the best you can with a Penske car, you should be running up front. That's really what I'm going to focus on.”

Americans Ryan Hunter-Reay (No. 28 DHL Andretti Autosport Honda, 1:17.0569) and Alexander Rossi (No. 98 Castrol Edge/Curb Andretti Herta Autosport Honda, 1:17.0817) rounded out the top five on a day when the Andretti team backed up its pace shown in Sonoma testing last week.

Rossi, however, saw his day end prematurely when he stopped on track, ending the afternoon session a few minutes early. Prior to that, Dale Coyne Racing’s Conor Daly (No. 18 Jonathan Byrd’s Hospitality Honda) suffered a mechanical failure that also brought out a red flag.

The third and final practice session ahead of Verizon P1 Award qualifying begins at 2 p.m. ET Saturday, streaming live on RaceControl.IndyCar.com with tape-delayed coverage at 5 p.m. on NBCSN. Verizon P1 Award qualifying airs live at 6 p.m. Saturday on NBCSN.

Coverage of the season-concluding GoPro Grand Prix of Sonoma begins at 6:30 p.m. ET Sunday on NBCSN and the Advance Auto Parts INDYCAR Radio Network.