Manor Formula 1 reserve Alexander Rossi admits he starts his IndyCar career this weekend in St Petersburg still getting acclimatised to the series.
Having raced exclusively in Europe, including five F1 starts with Manor and finishing second in GP2 last year, Rossi returns to race in his homeland in a joint venture between Andretti Autosport and Bryan Herta Autosport.
However, the deal was only finalised less than three weeks before the season opener, meaning Rossi missed almost all of the winter testing, only completing one session at Sebring.
He was 18th fastest in the first St Petersburg practice session, then 13th on Friday afternoon with a best time of 1m01.5198s, following a trip up an escape road.
Rossi's more experienced team-mates Marco Andretti and Ryan Hunter-Reay were 11th and 12th.
"The acclimation is still coming, trying to figure out how everything works," Rossi said.
"You know, it's fairly OK. First practice was about how it worked, format and such.
"At the end of the day it is a very nice car to drive.
"As I drive it more, have a better understanding of how it works, I'll start to enjoy it a little bit more.
"It was new in Sebring, now it's a new track. It's all coming at me a little bit quick.
"The experiences I've had so far, the biggest difference is speed more than anything. That's fairly predictable."
Rossi was the best of the three rookies in Friday's first sessions of the season.
Fellow F1 refugee Max Chilton was 22nd and 18th for Chip Ganassi Racing, with Indy Lights graduate Spencer Pigot was 19th and 22nd in his Rahal Rahal Letterman Lanigan entry.
Autosport Race Centre Live will bring you full coverage of the season opener from 4:45pm UK time this Sunday.