O’Shea was left to lament some poor defending from his side as a goal from Joao Felix and a well-taken double from Cristiano Ronaldo secured a routine victory for a dominant Portugal side.
“When you give a team with the quality of Portugal the goals that we did it is very frustrating,” he admitted.
“To win a game like this you cannot concede goals like that, especially from a set piece with that first one. Portugal normally play around the shape, but we let them get through us which was disappointing.”
The former Manchester United defender was also critical of his side’s lack of combativeness, particularly in midfield.
“The disappointing one was the duels we were winning against Belgium, Switzerland and Hungary we didn’t win tonight and that was frustrating.
“That caused the two goals as well as the marking in the box, but it shows the levels of where both countries are at.”