Force India admits it should've swapped F1 drivers in Canadian GP

As the pair pursued Red Bull's Daniel Ricciardo in third place, Perez was reluctant to voluntarily move over for Ocon, who was on fresher tyres.

Both drivers failed to pass Ricciardo and were also passed by Ferrari's Sebastian Vettel on fresh tyres after making an extra stop, falling to finish fifth and sixth.

While Force India never went as far as imposing a direct order on Perez to move aside, COO Otmar Szafnauer concedes it may have been better to have done so.

"Hindsight is a wonderful thing because you have more information," he said.

"What I would have done is perhaps swap them earlier - just after the Ferraris pitted. Do it then and it is easy.

"You can get your tyres back up to temperature and there is no risk from behind.

"Then, if it doesn't happen, you still have time to swap back.

"We didn't do that, we started discussing it a bit late and then after it was too late."

Szafnauer said pitwall debate was complicated because of concerns about losing time in a swap, and the risk of dropping tyre temperatures.

"You lose time when you swap, but more importantly, you lose tyre temperature - and tyre temperature is really critical," he said.

"So if you do that, you are not back up to speed straight away.

"We had the Ferraris charging, so there are ifs, ands and buts. Looking at it we, will analyse it.

"But had we swapped them I don't think Esteban would have got by [Ricciardo]."

MERCEDES: PEREZ PITSTOP WOULD'VE BEEN KEY

Mercedes strategy chief James Vowles believes Force India should have pitted Perez when Ocon came up behind him, dropping him in behind as a buffer for the Ferraris, rather than considering a swap.

Perez made his only pitstop on lap 19, while Ocon pitted on lap 32 and Ferrari's Kimi Raikkonen and Vettel made even later stops on laps 41 and 49 of the 70.

"If they had boxed Perez they would have come out ahead of Kimi just after he had stopped, and that would have then put them in the situation where they had removed the options for Ferrari," Vowles suggested.

"Ferrari now have a car that was on 60 laps tyres at the end of the race, a very compromised car.

"We saw [Romain] Grosjean make it [after stopping on lap one] but it is not the fastest race, and if Vettel boxes he now comes out behind Perez, which is a complicated decision.

"It leaves Esteban trying to attack Ricciardo for that P3 and if he is not successful, Perez would have caught up again and allowed him the chance to overtake with much fresher tyres.

"That would have generated a good opportunity for Force India."