Patrick on top in practice

The 25-year-old American was the quickest of the 26 drivers that took to the track during the day, lapping at 221.189 mph, as she and her Andretti-Green crew focused on race set-up.

"I'm the happiest I've been this month," Patrick said. "It felt like a race car. It was consistent in traffic.

"We're simulating race conditions, which generates confidence. If it's not windy, it won't change my attitude about the car. It's very good right now."

Ganassi racer Scott Dixon was second fastest, but was unable to break 221mph, while Sam Hornish Jr and Marco Andretti - who finished first and second in last year's race - were third and fourth fastest for Penske and AGR.

Dario Franchitti was fifth fastest for AGR with Ryan Briscoe next up for Luzco Dragon. TonY Kanaan and championship leader Dan Wheldon were seventh and eighth for AGR and Ganassi while pole-sitter Helio Castroneves and Tomas Scheckter completed the top ten for Penske and Vision.

Jaques Lazier in 15th was the fastest of the drivers who have yet to qualify for the race in his Playa del entry.

Jamie O'Leary