With 45 places separating Belgium and Slovakia in the Fifa rankings, this was statistically one of the biggest upsets in European Championship history.
The late VAR decision to rule out Lukaku’s equaliser because of handball by substitute Openda played a role.
Belgium boss Tedesco said he wanted to be a “fair loser” and did not want to give more of his opinion on the decision.
Christina Unkel, ITV Sport referee analyst, said: “The deliberation interpretation has recently changed.
“However, this is considered a deliberate offence as the arm is near the shoulder level because the arm is extended and the touch helps control the ball.”
But while Sutton believes the VAR decision was incorrect, he stressed that Lukaku had enough earlier chances to score.
“In truth, it was lousy from Lukaku in the first half. It was three huge opportunities that he normally gobbles up,” added Sutton.
“He could have had the Golden Boot [awarded to the tournament’s top goalscorer] wrapped up already. Slovakia haven’t actually created too many chances – but it is about Belgium being wasteful.”
Tedesco was not concerned, despite Belgium’s profligacy also playing a role in their premature group-stage exit at the 2022 World Cup.
“Lukaku’s been playing for Belgium for a long time and knows very well how to score goals. He showed that time and time again. Tonight he did score – but it was disallowed,” he said.
Doku’s mistake also proved costly as Belgium proved to be their own worst enemy on a forgettable night in Frankfurt.
“Of course it hurts. It hurts for him, for me and the team – but it’s part of the game. You will not score any goals without errors. It can happen,” added Tedesco.
“Slovakia had many errors tonight and that is why we have to score. We speak more about this error because it was the deciding goal.”
They have work to do now as they travel to Cologne to face group leaders Romania on Saturday, hoping to avoid another early exit from a major tournament.