If Max Verstappen wins the Japanese Grand Prix on Sunday, he will win his second world title.
The Red Bull driver held on to beat Verstappen's earlier time by a fraction of a second.
Verstappen made a mistake on his final lap, running wide at Turn Two, but held on.
The second Red Bull was behind the third one.
If Verstappen wins the race with the fastest lap, he will win the title.
If Verstappen doesn't win without the fastest lap, Leclerc will be second and the title will be Verstappen's.
Verstappen faces an investigation by the stewards after a scary moment with Lando Norris during the final session.
Verstappen almost lost control of his car on the exit of the flat-out 130R as he tried to get out of the way of Norris. When the Red Bull snapped, he had to go to the grass to avoid it.
Verstappen said that his tires were cold so he had a snap.
It was clear that Verstappen had tried to defend his position, according to the man.
Everyone agrees that people always precede the last corner. Everyone does it at one time or another. He told Sky Sports that he wouldn't have changed his mind if he were in his situation.
If he was in Verstappen's situation he would expect a penalty.
Verstappen said he had enjoyed F1's return to Suzuka for the first time in a year, despite concerns over the investigation.
Verstappen said it was great to drive here again. In the first sector, these cars come to life.
The first lap was enough and I lost a part of the duct in the second lap.
It was the fifth pole of the season for Verstappen. If he wins on Sunday it will be his 12th win of the year, which would be one short of the record for a season held by Michael and Sebastian.
With his final lap, Ocon jumped ahead of Lewis Hamilton's Mercedes and Fernando Alonso's McLaren to grab fifth place.
George Russell in the second Mercedes was eighth, followed by an impressive ninth from Sebastian Vettel in the Aston Martin on his final appearance at his favourite track, and Lando Norris' McLaren rounding out the top 10.
A new floor was installed in the Alpine. The team was optimistic that it was a significant step forward, but Alonso said it would be this race in Japan before its true potential would be shown.
On that basis, Alpine have reason to be happy - the car has looked quick all weekend, and Alonso was faster than Red Bull's Perez for much of qualification before dropping down the order a bit in the final session, and allowing Ocon to end up the faster of the two drivers
Mercedes suffered for the high drag levels of their car, and Hamilton and Russell said they were losing on the straights to the front- runners.
The car felt good. The balance was slow on the straight.
The car has been draggy all year. We are losing more time on the straights than the other guys but through the corners it was still enjoyable.
Russell said that they were losing a lot of lap time on the straights.
The first circuit that has long straights has high down force. Normally the circuits with the long straights - Spa, Monza, even Silverstone - you run low downforce, and the high-downforce circuits have short straights. The weakness has been exposed here.
After his decision to retire at the end of the season, Sebastian Vettel is having his last race on a track he loves and where he has won four times.
He thanked you very much as he came back to the pits.