Red Bull team boss Christian Horner said under-fire driver Sergio Perez had been in a "head-spin" in recent races and warned the Mexican that he needs to "realise his potential".

The 34-year-old Perez, who agreed a contract extension in May, was fourth in Friday practice for this weekend's Hungarian Grand Prix.

World champion and teammate Max Verstappen was second behind pace-setter Lando Norris in a McLaren.

In his last six races, Perez has contributed only 15 points for Red Bull compared to Verstappen's 119 while rival teams have improved and started winning.

"We all want 'Checo' to realise the potential that he showed in the first four or five races, and we know he's capable of that and that's why we took up the option early on him for next year to try and settle him," said Horner.

"I think he's been in a bit of a head-spin the last few races, but hopefully today showed signs that he's coming out of that.

"The team are working very hard to support him and to make sure that he does refind his form because we desperately need it."

Meanwhile, Verstappen declared he and Red Bull enjoyed a "good day" after the team introduced a set of upgrades, notably to their car's front wing, in a bid to boost raw pace and recover some overall lost performance.

"We had a good day," said the three-time world champion and series leader.

"Of course, there is still a lot to learn and optimise, but it's a solid start to the weekend."