Antonelli on top with a 1m06.202s, 0.4s ahead of Stroll. Medium tyres for the Italian.
He reports on team radio: "Something is not right, mate. My steering is pulling me massively to the right."
Second practice at the Red Bull Ring is now underway.
Lando Norris and Charles Leclerc are back in action for this session.
Young drivers took over their cars earlier on Friday.
George Russell insists it would be normal.

We're a few minutes away from being back on track.

Russell tops FP1 ahead of Verstappen, Piastri, Dunne and Gasly.
"It's raining in Turns 3 and 4. Very light," Piastri reports on team radio.
It's only ninth for the seven-time champion. Austria has been a weak track (in the dry) for Hamilton over the years.
Russell on top by less than a tenth ahead of Verstappen. Piastri, Dunne, Gasly, Bortoleto, Albon, Sainz, Hadjar and Antonelli is the top 10.
He goes fourth in the McLaren, 0.2s off Russell's top time. Dunne is currently top of the F2 standings.
Russell, Verstappen, Piastri, Gasly, Bortoleto, Albon, Sainz, Dunne, Hadjar and Antonelli.
Piastri goes second in the McLaren, a tenth off Russell.
It's Alonso, who's facing the wrong way. He manages to get going again with no damage to his car.
With 30 minutes on the clock: Russell, Bortoleto, Sainz, Antonelli, Hulkenberg, Piastri, Verstappen, Gasly, Lawson and Hadjar.
Russell returns to the top of the timesheets with a 1m05.776s on the softs.
He's told: "We've got an issue with the gearbox".
He's gone fastest for Williams with a 1m06.017s on the mediums.
Hamilton's first representative time of the session puts him 17th in the order, 1.4s off the pace.
Antonelli slots into second, 0.2s off his teammate. He's just complained about "front locking" over team radio.
Russell, Stroll, Antonelli, Alonso, Gasly, Albon, Sainz, Hadjar, Lawson and Hulkenberg.
Russell returns to the top of the order with a 1m06.537s. He's running on the hards currently.
Stroll back on top of the timesheets with a 1m06.853s, 0.2s ahead of Alonso.
A 1m07.140s for Russell on the hard tyre to go 0.2s ahead of Sainz. Verstappen slots into third, 0.5s off.