Showing no signs of rustiness following the summer break, rookie MotoGP World Championship leader Marc Marquez duly picked up where he left off at Laguna Seca by dominating the first day of practice for the Indianapolis Grand Prix.

A race winner around the Brickyard at Moto2 level in 2011 and 2012, Marquez once again wasted no time in adapting to faster MotoGP machinery as he topped both FP1 and FP2 aboard the Repsol Honda.

Bidding to secure a hat-trick of MotoGP wins in the United States, following success at Austin and Laguna Seca earlier in the season, Marquez was pleased to be the early benchmark in a Honda 1-2-3 but is certain there is more speed to come from the circuit.

"Today went pretty well," said Marquez. "After the break it was important to regain confidence on the bike. The truth is that I felt comfortable almost immediately. I tried to stay calm during the first few laps, as they are the most delicate and I'm happy with how the day went.

"The track improved a lot in terms of grip from session to session, so tomorrow we will likely see the times come down again. I think we're going in the right direction, so tomorrow we will likely see the times come down again. I think we're going in the right direction, so tomorrow we will continue as we have been doing so far."

Marquez holds a 16 point title lead over team-mate Dani Pedrosa, who was a close second fastest on Friday. LCR Honda's Stefan Bradl completed a top three covered by just 0.179s, with Jorge Lorenzo the leading Yamaha in fourth.