Four-time champion Scott Dixon has secured the sixth fastest time for the series-deciding IndyCar race in California.
Kiwi veteran Dixon is in second place and among five drivers in contention for overall honours when the title goes up for grabs at Sonoma Raceway on Monday morning (NZT).
The 37-year-old was solid but unspectacular on the opening day of practice, clocking a quickest time of one minute 17.3016 seconds for his Chip Ganassi Racing team.
Frenchman Simon Pagenaud, the series defending who is fourth overall, was quickest.
Brazilian Helio Castroneves (third overall) and Australian Will Power (fifth) were next-fastest on Saturday (NZT).
Series leader Josef Newgarden was ninth in practice and, like Dixon, will seek better in qualifying.
Dixon, who has only won once this year, moved within sight of the title when he placed second at the penultimate round in New York two weeks ago.
Team Penske driver Newgarden's lead evaporated when he hit a wall, clearing the way for a thrilling 85-lap finale in which double points apply.
Dixon was enjoying the theatre.
"It's not just one competitor, it's not two," Dixon told reporters before practice.
"We're going into the last race with five cars that have a pretty good shot at winning it."
Dixon, dubbed The Iceman, won his most recent title in 2015 in similar circumstances.
He won at Sonoma to move level in the standings with Juan Pablo Montoya, before being announced champion on a tiebreaker.
One more series title would lift Dixon to outright second on the all-time list behind seven-time champion AJ Foyt of the United States.