The shunt occurred with 50 minutes of the two-hour practice session remaining, when Legge (Rahal Letterman Lanigan Racing) and Wilson (Dreyer & Reinbold) made contact at Turn 1, just after Santino Ferrucci (AJ Foyt Racing) had passed Devlin DeFrancesco’s Andretti Autosport entry on the front stretch.
The cars appeared to slow as a result of that passing move, causing a concertina effect, and Legge’s left-front wheel ran into Wilson's right-rear corner as he checked up.
