Australia's Will Power found extra speed during Saturday morning's practice, then posted a four-lap qualifying average of 228.844 mph to tentatively grab the Indianapolis 500 pole.
Defending series champion Ryan Hunter-Reay is second at 228.282, with rookie Carlos Munoz of Colombia third at 228.171.
The start of qualifying was delayed about 2 ½ hours because of rain. All cars can attempt to requalify until 6 p.m. The nine fastest drivers will make another qualifying run in the pole shootout.
All five drivers from Andretti Autosport and all three from Team Penske finished among the top nine. Ed Carpenter is the only non-Penske or non-Andretti driver currently in the top nine.
The first 24 starting spots have been filled. The remaining nine will be filled Sunday.