It all went wrong, Cheika says after Argentina loss
England lost Tom Curry to an upgraded red card from the third minute, but not even playing a side down to 14 men could help an Argentinian team that suffered badly with ill-discipline.
George Ford was their punisher, hitting six penalties, as well as three excellently-taken drop-goals to convert territorial possession into points.
"Pretty much everything that could go wrong did go wrong. I think we let the play get too stop and start," said Cheika, who led Australia to the 2015 final and 2019 quarter-finals.
"England played the circumstances very well and full credit to them."
Argentina had come into the game at Marseille's Stade Velodrome as marginal favourites, ranked two places ahead of England in world rankings at sixth.
But a raft of handling errors, a misfiring backline and lack of discipline around the ruck cost them dear.
"There was almost no play. There were so many stoppages. The play we did get we didn't master every well," Cheika said.
"That was by design by the other team. They did it very well. They put us in that corner.
"We didn’t know how to change the rhythm, mainly because of our own mistakes. We'll take what we need from it and get on with the next game."
Cheika, whose Argentina side next face Samoa on September 22, added: "The world is not over. We still have work to do to qualify.
"Our players will take a lot from this experience. We have many first-timers in World Cup games and they will take a lesson of how we need to be ready when the whistle blows."
Argentina captain Julian Montoya, who plays his club rugby for Leicester, said the result was "obviously not the game we wanted, losing to a very good England team who did a lot of things well".
"But the attitude until the last minutes of the game was there so that is a positive.
"This is the first game of four. It’s a long tournament, of course, and things will need to improve as soon as possible. We need to be careful for the rest of the games."
England led 27-3 before Argentina claimed a late consolation try by Rodrigo Bruni, converted by Emiliano Boffelli.
"The attitude of the team to go until the last minute and score a try is important," Montoya said.
"We need to figure out why we didn’t do that for the 80 minutes.
"We are not at the standard we want to be at. It’s a bad thing to happen but it’s better that it happened in the first game. We can learn from it."