Takuma Sato topped a wet opening practice session for this weekend's IndyCar race on Detroit's Belle Isle street circuit.
The Rahal Letterman Lanigan driver, who crashed while attempting to pass Dario Franchitti for the lead on the final lap of last weekend's Indianapolis 500, managed a best lap of 1m28.4739s on a track covered with standing water after several hours of rain.
Only seven drivers set a time, with KV Racing's Rubens Barrichello finishing 0.3sec off Sato's benchmark in second place.
Justin Wilson (Dale Coyne Racing) completed a hat-trick of former Formula 1 drivers at the top of the timing screens by going third-quickest, although he also brought the session to a premature end when he hit the Turn 5 tires with a couple of minutes remaining.
James Hinchcliffe (Andretti Autosport), Simona de Silvestro (HVM Racing), Simon Pagenaud (Schmidt Hamilton) and Sebastien Bourdais (Dragon Racing) were the only other drivers to do any running, while a handful of others completed installation laps. No drivers from the Penske or Ganassi camps ventured out of pitlane.
Pos Driver Team/Car Time Gap
1. Takuma Sato Rahal DW12-Honda 1m28.4739s
2. Rubens Barrichello KV DW12-Chevrolet 1m28.8431s + 0.3692s
3. Justin Wilson Dale Coyne DW12-Honda 1m29.5754s + 1.1015s
4. James Hinchcliffe Andretti DW12-Chevrolet 1m29.6229s + 1.1490s
5. Simona de Silvestro HVM DW12-Lotus 1m30.9445s + 2.4706s
6. Simon Pagenaud Schmidt DW12-Honda 1m31.4855s + 3.0116s
7. Sebastien Bourdais Dragon DW12-Chevrolet 1m32.5644s + 4.0905s