Max Verstappen finished fastest in first practice for Sunday's Hungarian Grand Prix.
Verstappen edged out Valtteri Bottas by just 0.061 seconds, with Lewis Hamilton third in the other Mercedes.
Hamilton, eight points adrift of Verstappen in the championship standings, finished 0.167 sec behind his Red Bull rival.
The Formula One circus is back in action at the Hungaroring, a dozen miles outside of Budapest, 12 days after Hamilton's 180mph collision with Verstappen on the opening lap of the British Grand Prix.
Hamilton was handed a 10-second penalty for the accident, but the seven-time champion recovered from the punishment to take the chequered flag at Silverstone and reignite his bid for a record-breaking eighth world championship.
Speaking on Thursday, Verstappen was still angry with Hamilton's victory celebrations after he was taken to hospital following the crash which registered at 51G.
But the 23-year-old, whose team lost their appeal for the penalty to be reviewed, responded by laying down a marker in the opening action of the weekend.
The slow and twisty circuit is expected to suit Red Bull's strengths, but both Bottas and Hamilton kept Verstappen honest in the first running to suggest Mercedes should be in a position to fight this weekend.
Ferrari's Carlos Sainz finished fourth, half-a-second back, with Alpha Tauri's Pierre Gasly fifth. Gasly's team-mate Yuki Tsunoda crashed out of the session after losing control of his machine through turn five.
The action was temporarily suspended as Tsunoda's stricken machine was removed from harm's way.
Lando Norris finished ninth for McLaren, one second off the pace, with George Williams 15th in his Williams.