Power, who leads the IZOD IndyCar Series championship standings heading into the Indy 500, recorded the second-fastest lap of the day with a speed of 226.429 mph in the No. 12 Verizon Team Penske Dallara/Honda.
"Today was another great day - the best it's been all week," said Power. "The Verizon car feels great out on track, whether I'm in the draft or out on my own. I think we're prepared for Pole Day and I know I'm anxious to get out there and give it a go. Helio got the fast lap again today so I know all the Team Penske cars are capable of being on top tomorrow. I'm just hoping it'll be the No. 12 Verizon car."
Ryan Briscoe, who won the pole for the previous IndyCar Series race on May 1 at Kansas Speedway, posted the seventh-best lap of Friday's practice, which included 36 cars.
"It was a big day for us - we tried different cars, changed engines and we found some good speed," said Briscoe. "The No. 6 Team Penske car is getting better every time I go on track. I feel really good with the car that I have going into tomorrow and I am excited about having a fast car on Pole Day here at Indy."
Roger Penske's race team has won the pole position a record 15 times at Indianapolis, including Castroneves' pole win last year. The team has won the historic race 15 times, also a record. On Saturday, Team Penske will also be going for its fifth consecutive pole position this season.
Pole day qualifying is set to begin Saturday morning at 11 a.m. ET and will be televised live on Versus. This is the first time the event will employ a new format in which the fastest nine qualifiers will try again in the final 90 minutes of the day to win the pole position in a Pole Day Shootout. The session concludes at 6 p.m. ET.
The 94th running of the Indianapolis 500 is scheduled for Sunday, May 30 at 1 p.m. ET. ABC's live coverage of the event will begin at 12 p.m. ET.