Ferrari has admitted to making yet another strategy error in 2019.
Already criticised by the Italian press for a range of strategy mistakes this year, boss Mattia Binotto has confirmed that another oversight took place last Sunday in Canada.
In fact, Leclerc finished just six seconds behind Vettel on the track -- a single second away from snatching second place from the furious German.
"I did not know what was going on or that Seb had a penalty," Leclerc admitted to France's Auto Hebdo.
"I was just attacking in case something happened in front of me. I did my own race."
Boss Binotto admits that was an oversight.
"It was an error on our part. We were very busy on the wall and we missed it," he said.
The mistake and Vettel's lost victory aside, Leclerc said Ferrari has reason to be pleased with the outcome of the Canadian GP weekend.
"I think we were very fast," he said.
"It's a shame I made some mistakes in qualifying, which is something I have to work to improve. But the pace of the race was very, very strong so it's a good sign for the future."