Carlos Sainz remains hopeful of fighting his way back into the points in Sunday's Brazilian Grand Prix despite starting from the back of the grid following an engine issue in qualifying.

Sainz reported a loss of power during Q1 before returning to the pits, prompting McLaren to opt against sending him back out so it could properly investigate and define the issue without causing any damage to his engine or power unit.

As a result, Sainz is due to start Sunday's race from P20 on the grid. Teammate Lando Norris struggled to continue McLaren's recent good form in qualifying, finishing 11th in Q2 as the team failed to advance to Q3 for the first time since the Belgian Grand Prix in August.

While Sainz conceded the slow-speed nature of the middle sector at Interlagos was playing against McLaren, he remained hopeful of clawing up the order in Sunday's race.

"We’ve seen some trends this year, in some tracks, that there are certain types of corners where we are not very strong," Sainz said.

"Probably this track has many of these types of corners, which is why our relative performance drops depending on track to track.

"It doesn’t mean tomorrow we can’t make it back to the points, it just means it will be a lot tougher. Or tougher than Austria, for example, when it was a good one.

"It doesn’t mean we can’t do it. It means we need to do better."

Sainz said that while McLaren was yet to define the issue as it continued its investigations, but doubted there would be any changes in parc ferme that would require him to start the race from the pit lane.