Red Bull boss Christian Horner insists there was no reason Sergio Perez could not have followed Max Verstappen through the field to score points at Formula 1's Brazilian Grand Prix.
After another Q2 elimination in qualifying, albeit just a place behind team-mate Verstappen before the three-time champion's five-place grid penalty was imposed, Perez started 12th for Sunday's Grand Prix.
Yet after a race that included an early spin, another battle with potential successor Liam Lawson and a red flag delay, the Mexican could only manage to make up one place by the end of the race having lost out to Lewis Hamilton late on.
That was in stark contrast to Verstappen, who remarkably recovered from 17th on the grid to take his first victory since the Spanish Grand Prix.
"It was a difficult race for Checo," explained Horner in the aftermath.
"Spinning at the beginning of the race drops him down. It was an opportunity in the constructors to take a big chunk out of both Ferrari and McLaren and unfortunately, we've not been able to capitalise on that.
"Obviously, that's frustrating, but we'll go away and have a look at it and come back hopefully fighting hard in Vegas."
On whether there was a technical reason holding Perez back from matching Verstappen's charge through the field, Horner added: "Not that I'm [aware of]. There was nothing evident to me in the race."
Perez explained after the race that "we started the race with very cold tyres" and was immediately overtaken by the inspired Verstappen on the opening lap before his spin dropped him to the back of the field and into recovery mode.
Taking full wet tyres just before the red flag, where Verstappen stayed out on his starting inters, also meant he did not capitalise on the opportunity for a free tyre stop that aided his team-mate's victory bid.
"It was a total disaster," Perez said. "Really nothing worked."
The failure to reach the points in the Grand Prix, as McLaren and Ferrari remained ahead of Red Bull in the constructors' standings, has led to further pressure on Perez as his future remains in doubt.
At his request, Perez changed chassis in Brazil in a bid to rediscover his form, but could only qualify 13th for the dry sprint race before coming through to eighth in the 24-lap contest.
Asked whether Red Bull has now reached the point at which a driver change is a necessity, Horner replied: "Everything in life is subjective, you've got to look at the facts.
"We're working hard with Checo. He had a chassis change this weekend.
"I thought he drove a good [sprint] race but [the grand prix] wasn't his day."
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