SONOMA, Calif. -- Reigning IZOD IndyCar Series champion Ryan Hunter-Reay got off to a quick start in his quest to close the championship points gap by topping the time chart in the initial practice session for the GoPro Grand Prix of Sonoma.

Driving the No. 1 DHL car for Andretti Autosport, Hunter-Reay recorded a best lap of 1 minute, 18.6814 seconds on the 2.385-mile, 12-turn road course. Hunter-Reay is third in the standings with five races left, trailing front-runner Helio Castroneves of Team Penske by 65 points.

Click it: GoPro Grand Prix of Sonoma Practice 1 results

"We're working so hard to close the gap to the championship points lead so we're looking to make big gains this weekend," said Hunter-Reay, who has a best finish of eighth at Sonoma in 2010. "We had a promising top three going last year, until the final stages of the race when we were hit from behind, so we just need to pick up where we left off and improve the car."

Castroneves, driving the No. 3 Hitachi Team Penske car, was .0162 of a second behind Hunter-Reay. Dario Franchitti, who was fastest in the Open Test Aug. 21 on the course, was third overall (1:18.8124) in the No. 10 Target Chip Ganassi Racing car.

Practice 2 is scheduled for 5 p.m. (ET), with live Timing & Scoring with the IMS Radio Network broadcast available on www.indycar.com and the INDYCAR 13 app.

On Aug. 24, the third practice session begins at 2 p.m. (ET), followed by the three rounds of qualifying for the Verizon P1 Award at 5:30 p.m. (ET). A 30-minute warmup is scheduled for 1 p.m. (ET) Aug. 25, with the 85-lap race at 4 p.m.

NBC Sports Network will broadcast qualifications at 9 p.m. (ET) Aug. 24 and has the race broadcast at 4 p.m. Aug. 25.

Power, driving the No. 12 Verizon Team Penske car, set the track record of 1 minute, 17.2709 seconds in qualifying in 2012 on the 2.385-mile, 12-turn road course. Ryan Briscoe, who was driving for Team Penske, won the race last August. He's driving the No. 4 National Guard Panther Racing car this weekend.