Red Bull team principal Christian Horner assumes Lando Norris is the number one driver at McLaren because he is "paid five times more" than Oscar Piastri.

Despite Norris being the leading driver in the drivers’ championship standings and the highest-paid racer in the McLaren stable, it has been Piastri who has shone of late.

The Australian claimed his second career win in Baku last time out and has now scored more points (135) in the European leg of the season than any other driver. 

Piastri is now 32 points behind Norris in the standings, having taken five top two finishes in his last seven races for the British-based team. 

Ahead of the Azerbaijan Grand Prix, McLaren boss Andrea Stella revealed the team would favour Norris in a bid to topple Max Verstappen in the drivers' championship.

However, Horner rebuffed McLaren's claim that they have two number one drivers, suggesting Norris is being paid significantly more than Piastri.

"Usually those are things that are dealt with behind closed doors, those things, so I'm not actually sure what those rules are," said Horner. 

"There still seems to be some confusion in them. 

"Every team is different. Our rules of engagement are very clear and what the focus is until the end of the year.

"We've got a driver that's fighting for the world championship. It's a team sport. So it's very clear that Checo's job is to support Max until the end of the year.

"Different teams operate different ways. When you've got an asset like Max Verstappen, you don't make him a No 2 driver.

"Lando Norris, they're paying five times what they pay Oscar, so I would assume he would be their number one driver, or their biggest asset.

"So, therefore, the confusion comes when you're not up front from the beginning of what your plans are."

Thanks to McLaren's success in Baku, they now have a 20-point lead over Red Bull in the constructors' championship. 

The British-based team now lead the standings for the first time since 2005, but their way to the top has not come without its problems. 

During the Hungarian Grand Prix, Norris initially refused to hand first place back to Piastri before team orders were eventually followed to give the Australian his maiden victory in the competition. 

But with McLaren's comments about prioritising Norris for the last seven races of the season, Horner believes that decision should have come much sooner. 

"I think the other one is causing them headaches because he [Piastri] is winning races, and he's doing a very good job," continued Horner.

"It was like when Daniel Ricciardo came to us in 2014.

"He was clearly meant to be the number two to Sebastian Vettel, and he won three races that year to Sebastian's none. Sometimes it causes you a headache like that.

"For sure, they took Oscar with the expectation, as Mercedes probably did with George [Russell] and Ferrari did with Carlos [Sainz], that you've got a prime asset and a support asset.

"And when the second driver starts outperforming the first driver, that's when you tend to have a headache."