Having lost out to both Red Bulls despite a valiant defence, early race leader Sainz Jr found himself engaged in a thrilling duel with Ferrari teammate Leclerc to determine who would take the final spot on the famous Monza podium.
The pair almost took each other out on several occasions but Ferrari opted against intervening in their fierce battle, with Sainz just able to hold on to third place ahead of Leclerc.
And Sainz’s father thought the decision not to use team orders was odd.
“It’s curious,” Sainz Sr told DAZN on Sunday. “Sometimes they decide some things, sometimes others.
“It is he who has to ask and understand the strategies, why sometimes they can attack each other and other times not.”
“I more or less knew what the movie was going to be like, except maybe the last laps, which I didn’t expect,” he continued.
“I knew that the two Red Bulls were going to arrive very strong, and that Charles was going to be there.
“It’s been a weekend to be very happy. From minute one he has been there and making a podium with Ferrari in Monza is a very good result.”
Sainz Sr added: “I am left with the result and third place. Now that it has happened, I prefer it to be like this, without any type of order or anything. Deserved. Congratulations.”
Sainz and Leclerc agreed that their intense fight was “on the limit”, while Ferrari boss Fred Vasseur promised a review.
"For sure it's a bit of a strange feeling, but as you know, I'm a big fan of letting them race,” Vasseur told Sky F1 after the race.
"It was a great feeling. I told them no risk. The notion of no risk is always relative, but I really appreciated the last couple of laps and I hope that the fans did.
"As you can imagine, we'll have the discussion after the race, but perhaps not tonight - tomorrow they are in the factory."