Madrid were put to the sword in New Jersey, where La Liga neighbours Atletico led 5-0 at half-time in the pre-season fixture on Friday.
Diego Costa took centre stage with four goals before he was sent off, along with Madrid full-back Dani Carvajal, following a clash in the second half.
It was an incredible match at MetLife Stadium, where the margin of defeat could have been greater if not for some desperate defending and late goals from Karim Benzema and Javi Hernandez.
Discussing the result post-match, Madrid head coach Zidane – whose team conceded after just 43 seconds – told reporters: "What happened is that we entered the game very badly. A high-level competition, we entered very badly.
"At eight minutes we were down 2-0. There was no response from us to change something. The first part was difficult. We never entered the game. We have lacked everything. Especially intensity."
Zidane continued: "They scored seven goals, it can't happen. That is also known to the players, who are disappointed. You don't have to spin it over. It's a pre-season game. They've been better at everything. There is nothing more to talk about.
"We are preparing a season and being calm. We have to be on August 17, with the first league game. For now, we have lacked things for sure tonight."
Madrid, who overturned a two-goal deficit in a 2-2 draw with Arsenal after losing to Bayern Munich 3-1 in their pre-season opener, finished third behind champions Barcelona and runners-up Atletico in La Liga last season.
"We will be motivated. I have no doubt about that. Our season is going to be good. I am convinced," added the Frenchman, who saw Luka Jovic leave the game in the first half with an apparent leg injury.
"Today we cannot be happy. For the rest I am convinced that I have a team that will compete and very well. That's it. We have to go back and get some rest.
"It doesn't worry me, but it hurts. When you lose ... you don't play to lose. But that's it, we can't look back. It's a bad game and you have to think about what we've done."