Lando Norris was unimpressed with Max Verstappen's defending after picking up a penalty for leaving the track and gaining an advantage at the United States Grand Prix.

The two title contenders enjoyed a mighty battle during the closing stages of the race, but tempers flared when Norris attempted a move around the outside at Turn 12.

Verstappen jumped onto the radio immediately, calling for an investigation into Norris for overtaking off the circuit. The McLaren driver, meanwhile, complained that his rival forced him off the track.

But he received a five-second penalty, resulting in the McLaren star questioning Verstappen's aggressive defensive style.

Discussing the incident post-race with Sky Sports F1, Norris said: "It's impossible to know. They obviously can't make their minds up for a few laps. It's obviously not an easy decision otherwise it would have come a bit sooner.

"I tried [to overtake]. He also went off the track, so if he goes off the track clearly he's gone in way too hard and also gained an advantage by doing what he did."