Inter Milan manager Roberto Mancini has admitted that his side were complacent against Celtic after watching them twice throw away the lead during a 3-3 draw.
The former Manchester City boss believes that some of his players wrongly assumed that the Europa League last-32 tie would be an easy ride.
"Being two goals up and then 3-2 up, then drawing the game was disappointing. We played too much in our own half in the second half," Mancini told reporters.
"I was most happy with the way we started the game. At 2-0 up, maybe some of the players thought it was going to be an easier match than it was."
Despite being denied victory by John Guidetti's last-minute strike, Mancini remains confident that his side will secure their place in the last 16.
"It'll be a different game in Italy. Hopefully we can play the match as we started tonight and win the game. It won't be easy but playing at home will be to our advantage," he added.
Inter have now failed to defeat Celtic in their last four attempts.