Celtic manager Martin O'Neill struck a defiant tone despite his side's chastening 4-0 loss to Benfica, a result that exposed familiar frailties at both ends of the pitch and reignited scrutiny over the club's forward line.

The scoreline arguably flattered Celtic, with Benfica dominant for long periods and unlucky not to add further goals after striking the woodwork twice on top of their four strikes. The Portuguese visitors found space with ease against a Celtic defence missing the injured Cameron Carter-Vickers, as Gianluca Prestianni and Duran caused persistent problems for the home side's back line throughout the contest.

While the defensive shortcomings were evident, it is in attack where O'Neill may face his toughest decisions in the coming weeks. Club record signing Kasper Hogh endured another difficult outing and was withdrawn at half-time, extending a troubling run in which the Danish forward has now failed to score in 10 of his first 11 appearances since his summer move from Bodo/Glimt.

Hogh's withdrawal paved the way for a change in shape, with Duran moving into a more central role for the second half. The Colombian looked considerably more dangerous in that position, offering a sharper edge to Celtic's play going forward and giving the team a focal point it had lacked in the opening 45 minutes.

Former Celtic midfielder Scott Allan was unequivocal in his assessment of the contrast between the two forwards. "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," Allan said. He praised Duran's instinctive movement in behind defenders, adding, "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." Allan was more measured on Hogh, noting, "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." He also backed O'Neill's half-time call, stating, "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 himself acknowledged the growing sense that Duran's long-term future may lie through the centre of the pitch rather than out wide, a role he has often occupied at previous clubs. "[Duran] has played wide at his previous clubs," O'Neill explained after the match. "But I personally feel his best position is through the middle."

The Celtic boss suggested he is now exploring ways to accommodate his in-form forward in that central role on a more permanent basis, even as questions linger over how to manage Hogh given the financial investment made in bringing him to the club. "It's now a matter of us trying to fit him in and I think we can do that," O'Neill said. "It's a real battle for places now."

The defeat to Benfica represents another setback in a run of difficult results against stronger opposition, raising fresh concerns about Celtic's ability to compete at the top level of continental competition. With defensive injuries compounding attacking inconsistency, O'Neill faces mounting pressure to find the right balance in his squad, both in terms of personnel and tactical approach, as the season progresses.

Based on reporting from BBC Sport Football.