Juan Pablo Montoya admits that it will feel strange to return to NASCAR when he rejoins the Sprint Cup field with Penske at Michigan this weekend.
The Colombian spent six years racing stock cars with Ganassi before returning to single-seaters as part of Penske's IndyCar line-up this year, but has now added a limited Cup programme to his 2014 schedule too.
He said that the feel of a stock car will take some time to get reacquainted with.
"I don't know what to expect," he said. "It's going to feel weird.
"It's going to be fun to have the opportunity again with Team Penske cars, you look at Brad [Keselowski] ... they qualify in the top 10 every week, so there's a little bit of pressure. It's going to be interesting.
"I had only one day of testing in Nashville, so since Homestead [last November] I have driven the car once, but within five laps, I felt at home.
"They're a great bunch of guys. We're taking a really good car there. I got a lot of advice... it's hard to keep up. I'm being honest."
Montoya's third place in last weekend's IndyCar race at Texas was his career-best result at the track across all series.
His best Cup result at Michigan is a sixth in the June race in 2009.