Three drivers, representing the past four race winners at Twin Ring Motegi, were stashed in the top five of the speed chart as preparations began for the Indy Japan 300.

With a forecast of rain that could wash out final practice and qualifications for the PEAK Motor Oil Pole Award on April 18, the focus during two sessions of practice was on race set-up.

Reigning champion Tony Kanaan grabbed the top spot with a quick lap of 27.2453 seconds (200.842 mph) in the #11 Team 7-Eleven car for Andretti Green Racing.

Despite being quickest though he wasn't completely satisfied: "Overall, it was OK. We ran a full day and hopefully tomorrow will be better. I'm not quite happy with the balance of the car, but we still have two days to go and a lot of work to do," he explained.

"It's Turn 4 where I'm having the problem, so we're trying to make the car better there. Turns 3 and 4 are the key to have a balanced car for the race; that's where you're going to make the pass."

Scott Dixon meanwhile had a quick lap of 200.390 mph (27.3067) in the #9 Target Chip Ganassi Racing car, while two-time Motegi winner Dan Wheldon (200.250; 27.3259) was third.

"We basically tried to make changes between the sessions to try and make the car better. We came up with a few things because to start off, the car was difficult to drive," Dixon reflected.

"We actually ran out of tyres with about 10 minutes to go. We had to do another sticker run at the end, which we really didn't want to do, and then we caught some rain, so I don't think we got the optimum speed out of the car. I think we could have easily got into the 201's without the weather. That was the only frustrating part of the last session."

"It was a relatively good day," added Wheldon. "Unfortunately, we didn't quite get our second set of tyres on in that second session. I think what you can see is we've let the car (be) on edge a little more. With that, it's probably good that we did save that set."

Team Penske's Helio Castroneves, the pole sitter last year and points leader coming into the 200-lap race, was fourth (200.032; 27.3556), while Vision Racing's Ed Carpenter (199.737; 27.3960) rounded out the top five.

"Today was an interesting day. The Team Penske car started off good, but then we faced a little problem," stated Helio. "That's why we weren't able to do as many laps, and obviously, the rain made it a little harder on everyone. But right now, we have a good car for the race and we'll see what happens with the weather."

Further down the order Marco Andretti was sixth (199.675; 27.4046), closely followed by Ryan Briscoe (199.244; 27.4638) and Danica Patrick (198.870; 27.5155), while Townsend Bell (198.005; 27.6356) and Hideki Mutoh (197.794; 27.6651) were ninth and tenth.

"I think we still have a bit of work to do, but it's been good for me just learning the track again," noted Briscoe.

"It's a pretty difficult circuit. Team Penske spent the day working on the setup, making gains and moving up in the field a little bit as we go. I'm really happy at how we finished after day one."