Although Celtic conceded four, the scoreline did not flatter Benfica. The Portuguese side created chances aplenty in both halves and hit the woodwork twice in addition to their four goals.
Celtic’s lack of depth in defence was exposed once again in the absence of the injured Cameron Carter-Vickers as Gianluca Prestianni and Duran tormented the visitors’ back four.
However, it is in forward areas where O’Neill perhaps has his biggest headache.
Club record signing Kasper Hogh was hooked at half-time and has now failed to score in 10 of his first 11 outings since joining from Bodo/Glimt in the summer.
Duran shifted inside for the second half and posed far more of a threat than his Danish team-mate.
“If I’m a creative midfield player and I’ve got Duran and Hogh to pick from, I’m taking Duran every day of the week,” former Celtic midfielder Scott Allan said.
“He looks to get off the side of defenders, if you put a ball in the area, he’s more likely to be alive to it.
“Hogh just isn’t firing on all cylinders. I can take that if he’s doing the other side of the game a lot better than he is.
“You can see why Martin O’Neill made the substitution at half-time and there’s no doubt Celtic looked much better going forward.”
O’Neill admitted he sees Duran as being better through the middle, when asked about his Colombian talisman post-match, but given Hogh’s price tag he might not be inclined to pull him out of the firing line just yet.
“[Duran] has played wide at his previous clubs,” O’Neill said. “But I personally feel his best position is through the middle.
“It’s now a matter of us trying to fit him in and I think we can do that. It’s a real battle for places now.”