The Italian Grand Prix was won by Red Bull's Max Verstappen, who continued his dominance of the championship.
The Italian team tried a two-stop strategy that backfired and gave the lead to Verstappen twice.
Verstappen's 11th win of the year puts him 115 points ahead of Leclerc and he could potentially win the title in Singapore.
George Russell's Mercedes took third place, ahead of the Mercedes of Lewis Hamilton and the Mercedes of Carlos Sainz.
After a penalty for excessive engine usage, Verstappen moved up quickly from seventh on the grid and was second after five laps.
He was close to Leclerc until a virtual safety car was put in place on lap 12.
Although they stopped as the VSC was ending, they did not gain all of it because they gambled on a stop.
Verstappen didn't come in for his stop for tires until lap 25.
Verstappen came out 10 seconds behind Leclerc and began to close on the car. Within seven laps, he had erased the lead to just over five seconds and was ready to pass Leclerc.
On lap 33, Leclerc was called in again by Ferrari, hoping to close the gap on Verstappen over the rest of the race.
A full safety car was deployed with five laps to go after Daniel Ricciardo's McLaren broke down and stopped at the Lesmo corners.
The race ended under the safety car because officials couldn't restart it in time.
There will be questions as to why the safety car initially picked up Russell instead of Verstappen, why it took so long to run through the procedures required to restart the race, and why officials could not have red-flagged the race.
Verstappen needs to leave Singapore within three weeks to win the title.
He would have to win the race to become champion.
Verstappen has taken total control of this season and he and Red Bull have established such an advantage that they seem to be almost unbeatable.
If Leclerc doesn't run into technical problems, he could finish on the podium.
Hamilton began to pick his way through the backmarkers after Sainz made the most eye-catching progress.
Sainz and Hamilton moved up into the fourth and fifth places as the rest of the field made pit stops.
Red Bull'sSergio Perez followed them in sixth place from 13th on the grid despite a pit stop and a brake fire.
Pierre Gasly's Alpha Tauri was the beneficiary of the retirement of Fernando Alonso's Alpine and took eighth place.
On his debut for Williams, Nyck De Vries drove very well.
After Alex Albon was diagnosed with appendicitis, the Dutch driver was drafted in and was promoted from 13th to ninth and went on to win the race.