Two-time Formula One champion Fernando Alonso crashed in practice Thursday while IndyCar season points leader Scott Dixon soared atop the Indianapolis 500 speed chart ahead of weekend qualifying.
Tension grew at Indianapolis Motor Speedway as Spain's Alonso was unhurt after being involved in the first crash at the famed 2 1/2-mile (4km) oval in two days of practice runs.
"You learn every lap you do around here, and we learned from this," said Alonso. "Tomorrow we start again. I think everything tomorrow is going to be OK. Let's keep up the good work, and hopefully no more issues."
New Zealand's Dixon ran the fastest lap so far with a top lap of 39.8050 seconds, reaching 226.102 mph in his Honda-powered Dallara.
"We made some minor changes and tried to figure out some different balances," Dixon said. "We're also focusing on how the car feels. We're just running through those variations and trying to run in as much traffic as possible and get the car as comfortable as possible for the race."
Alonso was fifth fastest in Wednesday's first practice session and posted the eighth-best speed Thursday at 224.363 mph before the accident, which came 50 minutes before the end of practice.
Alonso's Chevrolet-powered Arrow McLaren made contact with the turn four outer wall after clipping the concrete with his left front wheel.
The car did a half spin to the left at the entry to the pit lane and slid into the inside pit wall, making right front contact again and coming to a stop with moderate damage.
"It was the car, the grip of the car," Alonso said. "This place, the walls are coming very close. This is the way it is."
Alonso is trying to join England's Graham Hill as the only drivers to win the 24 Hours of Le Mans, the F1 Monaco Grand Prix and the Indy 500.
This year's race was moved from May 24 to August 23 due to the COVID-19 pandemic and will be contested without spectators.
The Spaniard, who started fifth in 2017 and finished 24th after leading 24 laps, also crashed in practice last year, when his car failed to qualify for the 33-car field.
"Unfortunately, it happened again today," Alonso said. "Hopefully it happens today instead of Sunday the 23rd."
Dixon won the first three races of the COVID-19 delayed 2020 campaign and has 244 points in the standings to 195 for second-place Simon Pagenaud, the defending Indy 500 champion.
Dixon was third-fastest Wednesday at 224.047 and looks to be a contender for pole position this weekend as well as a second Indy 500 victory.
"We're really just working hard on race setup," Dixon said. "We also worked on finding traffic today to see how the car would respond."
Japan's Takuma Sato was second overall Thursday at 225.693 mph with Marco Andretti third at 225.249, both with Honda power.