Williams driver Carlos Sainz has been given a five-place grid drop for the Mexico City Grand Prix following his collision with Kimi Antonelli at the US GP on Sunday. The stewards have also handed the Spaniard two penalty points, as they deemed that he was at fault for the incident with the Italian rookie at Turn 15.Sainz made a brilliant start to the US GP at COTA as he moved into P8 in the initial stages of the race after having started from ninth. But the driver failed to make any progress as he crashed out after a collision with Antonelli's Mercedes soon after.The 31-year-old made an overambitious move at Turn 15 and tried to overtake Antonelli, but ended up colliding with him and getting locked up on the inside. This resulted in a DNF for Sainz and also a post-race investigation for causing a collision.After the race, the stewards deemed that Sainz was predominantly at fault for the collision and handed him a five-place grid penalty for the next race, the Mexico City GP. He has also received two penalty points on his super license.The stewards noted that the front axle of Sainz's Williams was not alongside Antonelli's Mercedes at the apex. This means that he had not earned the right to be left space on the corner, according to the Driving Standards Guidelines.Since Sainz's race ended immediately after the accident, he was unable to serve any penalty during the session. Unfortunately for him, he has carried the penalty to Mexico. This marked a disappointing end to Sainz's US GP weekend, which was otherwise extremely positive, thanks to his P3 finish in the Sprint on Saturday.Carlos Sainz reflects on race-ending incident with Kimi Antonelli at the US GPCarlos Sainz and Kimi Antonelli during the US Grand Prix - Source: GettyCarlos Sainz said he got "a bit scared" by Kimi Antonelli turning into Turn 15 a little earlier than he had anticipated, leading to their crash during the US GP on Sunday. The Williams driver also claimed that the incident looked worse than it was.Speaking to the media after his race ended, Sainz said (via Motorsport.com):"I think he started closing the door earlier than I expected and I ultimately locked up and got a bit scared by him closing on me and yeah, we collided.”"I think the incident looks a lot more bad than what it actually is because in the end it's just a small lock-up with high consequences, but a pity because we're coming on a good weekend," he added.Carlos Sainz will now have a five-place grid penalty at a track where the Williams team is expecting to be strong. The Grove-based outfit currently sits fifth in the constructors' standings with a healthy 39 points buffer to Racing Bulls in sixth.Sainz is 11th in the drivers' standings, 35 points behind teammate Alex Albon, who sits in P8.