The 22-year-old Dane had a clean session in comparison to his rivals, going to the top with a flying lap at 1m07.6154s around the 11-turn, 2.238-mile road course.
Rinus VeeKay (Ed Carpenter Racing) ended up second, trailing by 0.0392 of a second. Newly crowned two-time IndyCar champion Alex Palou was the best Chip Ganassi Racing driver in third.
Arrow McLaren’s Alexander Rossi was fourth, while Andretti Autosport’s Kyle Kirkwood rounded out the top five.
Red flags became the theme once again in Saturday morning’s session.
The first stoppage came out after nine minutes when McLaren’s Pato O’Ward got out of shape entering Turn 3, skidding off course into the tyre barrier with minor damage to his car’s left front corner.
“It’s just a driver mistake, I think I touched a white line on the curb,” O’Ward said after his mount was towed back to the paddock. “It was just too much attack for what was available.”
Colton Herta put his Andretti Autosport Honda at the top moments before O’Ward’s shunt with a lap at 1m07.8880s. The session resumed after a 7m33s stoppage, with Rossi flexing the strength of his #7 Arrow McLaren Chevrolet and vaulting to first with a flying lap of 1m07.8522s.
A second red flag came after Will Power lost control of the backend of his Chevrolet-powered Team Penske entry entering the Corkscrew, drifting backward into the gravel before coming to a stop at top of the hill.
Colton Herta, Andretti Autosport w/ Curb-Agajanian Honda
Photo by: Jake Galstad / Motorsport Images
The session resumed after a five-minute break. The pace was briefly set by VeeKay before Lundgaard’s pace-setting lap.
With 13 minutes remaining, the #14 AJ Foyt Racing Chevrolet of Santino Ferrucci erupted with a plume of smoke and stopped in Turn 11 to bring another red flag.
There were several further off-course adventures for many drivers, with Turn 10 proving to be the tricky spot for the likes of Herta, Ryan Hunter-Reay and Graham Rahal, among others.
The #30 Rahal Letterman Lanigan Racing Honda of Juri Vips was hit with a six-position starting grid penalty by IndyCar officials on Saturday morning following an unapproved engine change after yesterday’s practice.