Rahal lapped in 1m10.1132s and will start ahead of team-mate Christian Lundgaard and Alexander Rossi of Arrow McLaren.
It wasn’t a great qualifying for championship frontrunners Alex Palou, who will start from the fifth row in ninth place, and Josef Newgarden, who will start down in 19th after he failed to make it past Q1.
Fast Six qualifying
Devlin DeFrancesco set the early pace at 1m10.8193s but Lundgaard beat that with 1m10.5858s with the first lap of his second run. Rossi and Pato O’Ward then took turns at P1, before Lundgaard unleashed 1m10.2286s to wrest it back.
But Rahal wouldn’t be denied, producing 1m10.1132s for his first pole position in six years.
Lundgaard will start alongside him, ahead of the Arrow McLaren duo of Rossi and O’Ward, and the Andretti Autosport entries of DeFranceso and Romain Grosjean.
Top 12 qualifying
Rahal grabbed the fastest lap on his final lap of the session with 1m09.9837s, ahead of Lundgaard, Rossi, Grosjean, O’Ward and DeFrancesco.
Falling at this hurdle were Marcus Armstrong (Ganassi), Jack Harvey (RLLR – who has a six-place grid penalty), Alex Palou (Ganassi), Felix Rosenqvist (McLaren), Scott McLaughlin (Penske) and Helio Castroneves (Meyer Shank Racing – who also has a six-place grid penalty).
Group stage qualifying
In Group 1, DeFrancesco was fastest with a time of 1m10.2805s, ahead of Harvey, O’Ward, McLaughlin, Rossi and Rosenqvist.
But the big news was title contender Newgarden missing the cut, and he was only 10th fastest.
Missing out were Colton Herta (Andretti), team-mate Kyle Kirkwood, Will Power (Penske) and team-mate Newgarden, Santino Ferrucci (AJ Foyt Racing) and the Dale Coyne Racing cars of David Malukas (who has a six-place grid penalty) and Sting Ray Robb.
In Group 2, Lundgaard set the quickest time at 1m10.0031s from Rahal, Grosjean, Castroneves, Palou and Armstrong.
Making no further progress were Linus Lundqvist (MSR), Scott Dixon (Ganassi), Marcus Ericsson (Ganassi), Ed Carpenter Racing’s Rinus VeeKay and Ryan Hunter-Reay, Juncos Hollinger Racing’s Agustin Canapino and Callum Ilott, and Benjamin Pedersen (Foyt).