Ivan Schranz's seventh-minute finish in Frankfurt proved the difference as Slovakia stunned the world's third-best side in their tournament opener.

Belgium forward Lukaku produced a profligate showing, spurning a pair of glorious first-half chances before seeing two goals disallowed by the VAR as Tedesco's side chased a late equaliser.

Lukaku accumulated an expected goals (xG) tally of 0.82 throughout the Group E meeting, with that total far greater than the entire Slovakia team combined (0.59).

Yet Tedesco, who suffered a first defeat in 15 games since replacing Roberto Martinez as Belgium boss, did not pinpoint specific players when discussing Belgium's downfall.

"For me, it hurts a lot," Tedesco said. "I don't want to point the finger at people. You can be sure we will speak about many things but we will do it internally and not through the media.

"I knew we would lose one day but unfortunately it was today. Honestly, there is not much I can say to the team to improve.

"We created many chances, big chances. Of course, if we take one, then it makes the game easier."

When pressed on Lukaku's form in front of goal, Tedesco defended the former Chelsea and Manchester United striker.

"Romelu has been playing for Belgium for a long time," the Red Devils coach said. "He knows how to score goals, I don't need to tell him that. He is a top-class player with great character."

Lukaku saw his first effort ruled out for an offside after Amadou Onana's headed knockdown before his late finish was again overturned as Lois Openda was deemed to have handled in the build-up.

"It's tough to speak," Tedesco said. "If we had won I could tell you more about my opinion.

"But we lost and I want to be seen as a fair manager so I don't say anything. We have to trust these guys. I trust the VAR. If they decide it's handball, we have to accept it."

Belgium's defeat leaves Group E wide open after Romania hammered Ukraine 3-0 on the same day, with Tedesco's side needing a response against Edward Iordanescu's team on Saturday.

Another loss would push Belgium further towards an unlikely group-stage exit, though Tedesco wants to use the Slovakia disappointment as motivation.

"Naturally everyone is disappointed but you can harness that," he said. "You can make use of it. I always said our group would be very tricky and shouldn't assume that we will go through."

Belgium captain Kevin De Bruyne was also frustrated as his side suffered its first group-stage defeat at the European Championship since losing 2-0 to Italy in 2016.

"It is a pity," he said. "The first 20 minutes we were really good and we made such a mistake for which we were punished.

"In the second half it was better, we upped the tempo. We deserved to win but did not score and that is the way it is. Apart from a few other chances we didn't give much away.

"We adjusted some things at half-time and then played well. We pushed, we created chances. We certainly deserved to at least a draw because we didn't play badly."