Helio Castroneves and Graham Rahal swapped top honors in today’s two practice sessions for the Chevrolet Detroit Grand Prix presented by Lear.

Castroneves led this afternoon’s final practice before qualifying for the first race of the Verizon IndyCar Series doubleheader weekend. Driving the No. 3 Hitachi Team Penske Chevrolet, Castroneves clocked a best lap of 1 minute, 15.1511 seconds (112.573 mph) that stands as the fastest of the day.

Rahal led the morning session in the No. 15 SoldierStrong / TurnsforTroops.com Honda (1:15.3328), with Castroneves second. The order flipped in the afternoon’s 45-minute session on the 2.35-mile, 14-turn temporary street course, with Castroneves first and Rahal second (1:15.3519).

Alexander Rossi, in the No. 98 Andretti Autosport/Curb Honda, ran the third-fastest lap this afternoon (1:15.4323) before his car spun midway through the session and made contact with the wall in Turn 8.

“It was just loose in entry, I guess,” Rossi said. “It’s a weird place to spin, especially on entry, so it just got away from me. I don’t think the car is too bad, but that’s a concrete wall there.”