Ganassi's Scott Dixon and Dario Franchitti made an early impact in proceedings at Mid-Ohio Sports Car Course in first practice on Friday ahead of this weekend's Honda Indy 200.
Romain Grosjean put Lotus at the top of the time sheets in Saturday morning practice ahead of Ferrari's Fernando Alonso, before a late yellow for a crash by Sergio Perez in the McLaren.
Kurt Busch will start from pole position for this weekend's Southern 500 Cup race at Darlington Speedway after setting a new track record in qualifying.
Racing Engineering's Fabio Leimer set a blistering lap early in the Friday practice session that left him a full second clear of the rest of the field.
Organisers of the IndyCar Grand Prix of Balitmore have said that they will reintroduce a chicane on the frontstretch, after cars were launched into the air over railroad tracks.