Red Bull monitoring Mercedes rear wing after Lewis Hamilton's 'mind-boggling' pace

SAO PAULO, Brazil - Red Bull boss Christian Horner said Lewis Hamilton's blistering charge through the field during Saturday's sprint race is why his team has suspicions about Mercedes' rear wing.

The rear of the world champions' car has received a lot of attention this week. After qualifying quickest on Friday, Hamilton was disqualified from the result of that session when the Drag Reduction System (DRS) on his rear wing opened by 0.2 millimetres more than the 85mm allowed in the regulations.

While the FIA race stewards who handed out the disqualification said it was clearly a broken wing, and not an attempt to cheat, Red Bull has taken a close interest in that part of Mercedes' car for a few weeks now. Red Bull is understood to have raised an enquiry with the FIA earlier this week ahead of the Sao Paulo Grand Prix.

That might help explain why championship leader Max Verstappen inspected and touched the rear wing of Hamilton's car after qualifying, something which ultimately landed him a 50,000 Euro fine.

Speaking on Saturday after sprint qualifying, Horner said Hamilton's pace in the sprint race showed why the team is curious.

"To be honest it's no real surprise because we saw it [on Friday]," Horner told Sky Sports. "Lewis' straight-line speed is just mind-boggling."

When asked what the team was seeking clarity from the FIA on, he said: "It's something that is enabling the car to do that kind of speed. Something must happen because physics wouldn't allow....

"The kind of horsepower delta that you would need to achieve that, would be pretty significant. So we're obviously trying to understand what it is and go from there."

Horner said Mercedes has been showing signs of performance gains for a while.

"We've seen this coming for a few races now. Turkey, it started to be there. In Mexico, we saw the straight-line speed, I think they were about 14 km/h quicker at the end of the straight than we were, so it's no great surprise. "We saw yesterday that it's phenomenal, especially with the size of the rear wing that they have on the car. It's something that we've got to try and focus on our own performance."