Manager Peter Houston feels not being able to score at two crucial periods of the game harmed Dundee United's chances in
Gary Mackay-Steven missed an early chance before Celtic netted twice in the run-up to half-time.
Houston remained confident of a comeback, until two further goals completed Celtic's victory.
"When you come here you always want to take the chances you create," said Houston.
"Who knows what would have happened had we scored?
"If we score first it puts them on the back foot.
"But even at 2-0 at half-time I said the next goal was all-important and I felt that Celtic were getting a wee bit edgy at times.
"If we get that next goal we are back in the game but they got the third goal and the game is over and done by then."