Ryan Briscoe led the way with the fourth-fastest lap Monday - a 225.016 mph effort in the No. 6 IZOD Team Penske Dallara/Honda.
"It felt great to be back on track today," said Briscoe who also topped the Team Penske trio in Saturday's opening day of Indy 500 practice before rain cancelled all on-track activity on Sunday. "We took out our primary No. 6 IZOD Team Penske car for practice, and it felt very comfortable out there. It's nice to be in the 225 bracket. We'll keep chipping away at it for the rest of the week and get ready for qualifying on Saturday."
Three-time Indy 500 winner Helio Castroneves had the eighth-fastest lap of the 39 cars on track Monday, as he posted a 224.348 mph run in the No. 3 Shell V-Power Pennzoil Ultra Team Penske machine.
"It was a good day today in the Shell V-Power Pennzoil Ultra car," said Castroneves, who will fight for his fifth career Indy 500 pole on Saturday. "We got a chance to run side-by-side with Will (Power), and we were pretty happy with the car. We stuck with our plan to run the primary car. Hopefully tomorrow the weather cooperates and we'll continue to work hard and get ready for qualifying."
Driving the No. 12 Verizon Team Penske Dallara/Honda, Will Power was 10th-fastest in practice with a lap of 223.984 mph.
"We did limited running again today in the Verizon Team Penske car," said Power, the IZOD IndyCar Series championship leader. "We're just trying to use our miles wisely. We worked on some race setup today and the car feels good. We still have plenty of time on track this week before we qualify on Saturday, and we plan to make the most of it."
Power saw the most action of the day among the Penske pilots as he ran 34 laps. Castroneves ran just 32 laps in practice while Briscoe logged 29 laps at the 2.5-mile superspeedway.
Practice resumes on Tuesday at 12 p.m. ET, with qualifying scheduled to begin Saturday at 11 a.m. ET. The 100th anniversary Indianapolis 500 will be run on Sunday, May 29.