McLaren's Carlos Sainz fears the engine issue that deprived him of crucial mileage in FP1 will impact the remainder of his Monaco weekend.
An energy store replacement on his Renault power unit kept Sainz stranded in the McLaren garage in Thursday's opening practice session, the Spaniard managing a total of just four laps.
His running was consistent and trouble-free in the afternoon but the McLaren driver still rued the lost time and mileage, and feared it could prove costly for qualifying.
"Monaco is the last place you want to miss FP1 and stand still for one and a half hours while the others get laps on you," Sainz said.
"I am 30 or 40 laps behind, but the mechanics did a brilliant job to get me back out on track right at the end to get an installation lap, but those 30 or 40 laps that I am behind are going to hurt further into the weekend. Hopefully we can recover little by little."
Sainz best lap in FP2 was just 0.026s slower than team mate Lando Norris and good for P13. But given the tightness of the field at Monaco, McLaren will require significant gains for its drivers to challenge for a spot among the top ten.
"Quali is what really matters and there is still margin to work and improve," added Sainz.
"On one side it looks difficult as we haven’t been in the top 10 or Lando hasn’t been in the top 10 in FP1 or FP2.
"But at the same time if it is close, and it is pretty close, we could be up there.
"As soon as we get my confidence up and my lap mileage up maybe all of sudden we can turn up a bit of pace."
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