Charles Leclerc took a popular podium at Imola, with Carlos Sainz in fifth, as Ferrari was beaten by McLaren as F1's closest challenger to Red Bull's Max Verstappen.
With overtaking nearly impossible on similar tyre strategies, Ferrari feels it effectively lost the battle for the Emilia Romagna Grand Prix in qualifying, with Vasseur saying: "I think that if we do 1-2 in qualifying, we do 1-2 in the race."
Leclerc and Sainz qualified fourth and fifth respectively, moving up one spot on the grid due to Oscar Piastri's grid penalty.
But while Leclerc rued a imperfect power delivery setting that made the red cars bleed laptime on the straights compared to both the Red Bulls and the McLarens, being only two tenths off in fourth suggests that F1 now really has a battle on its hands between three teams.
In fact, Verstappen's pole time was boosted by a tow from Haas' Nico Hulkenberg which may well have prevented an all-McLaren front row. That would have reduced the spread between the three teams to just over a tenth.
Vasseur says that one-tenth gap means teams will now have to accelerate development plans even further. Bringing just the tiniest upgrade can help make the difference as the rate of development slows under the current regulations.
"What is true is that we are at the point now where we will have to speed up the development," said Vasseur.
"Imagine that someone could bring an upgrade one race [earlier] when you have three teams in one tenth, you can jump from P5 to P1.
"It means that we'll have to speed up the time to market, it will be crucial.
"But we also have to pay attention that we are now chasing the last hundredths. It's not anymore a five-tenth upgrade.
"It means that you also have to be sure that what you are bringing is working. It will be the key factor for the next couple of events."
As focus shifts to the tiniest details, it also gives various departments, whether they be drivers, factory support teams or strategists, all the power to make a difference.
"When you are three [teams] in one tenth, every single bit can make the difference," Vasseur added.
"I think that the competition will be everywhere. The set-up of the car will be crucial next week in Monaco, the performance of the driver will be crucial.
"It's good news for F1, good news for the championship. You have three teams in seven seconds after seventy laps. It's less than one tenth a lap."
Vasseur cautioned that Ferrari will need more race weekends to properly judge how well its comprehensive Imola upgrades have delivered.
But there was a hint of frustration that whatever the Scuderia has been able to bring to the SF-24 has already been matched by McLaren since its breakthrough Miami upgrades.
"Overall, it's mixed feelings for me because everything that we did a step forward [on], McLaren did probably the same as us."
"We compensated partly the delta with Red Bull, we are not far away."
