Shanghai track has 'exposed' weaknesses of McLaren's F1 car

Both Sainz and his team-mate Lando Norris showed well in Friday's second 90-minute practice session but even this came as a surprise, and come qualifying neither driver made it through to the top-10 shootout.

The team has appeared to be on an upward trajectory in the early part of the 2019 season after four particularly miserable campaigns, but the characteristics of the Shanghai circuit punished shortcomings in the McLaren-Renault package.

"We knew before coming here that this track could expose our weaknesses a lot more than the other two tracks so far this season," said Sainz.

"So we kind of expected not to be weaker but to struggle a bit more.

"Probably FP2 yesterday gave us more encouragement than it should have and today we came back to reality."

Sainz and Norris were sixth and eighth fastest during Friday's second practice session.

Asked by Autosport whether Saturday's relative slump was caused by McLaren being unable to replicate its Friday performance, or simply by rivals finding more pace, Sainz confirmed that the team was still investigating.

"There's a bit of analysis to look into why we were that competitive in FP2 and then on Saturday we went back to where we'd expected to be," he said.

"No big surprises, just some analysis to be done.

"On Thursday I knew at this track, [reaching] Q3 would be a lot more challenging, it's just that on Friday being P6 and P8 [in FP2] got all of us very encouraged. Maybe we wouldn't be as bad as we thought at this track.

"But coming into Saturday it's fair to say we were not as quick as we would like."

Norris said Shanghai's long straights, combined with two particularly long corners that stress the front-left tyre, were the key to McLaren's troubles.

"Although there are not loads of corners here compared with Bahrain or Australia, we aren't fastest on the straights but we're definitely not fastest in the corners," he said.

"So there is a lot of work to do to get the car better but that is obvious and has been since the beginning of the season."

Sporting director Gil de Ferran also said the performance was a factor of circuit characteristics.

"This circuit is more dominated by long corners, and so in that way this circuit is different to Bahrain and Australia," he said.

"Obviously we wish we were a little bit quicker but we understand fairly well what our weaknesses were coming into this weekend."