Martin O'Neill conceded Celtic's depleted team are running on empty and insisted that January signings are crucial if they are to compete on all fronts this season. 

O'Neill's comments came ahead of Celtic's Europa League clash with Utrecht, where a win on Thursday will be enough to see them qualify for the play-offs. 

The likes of Kelechi Iheanacho, Alistair Johnston, Cameron Carter-Vickers and Jota are just some of the names unavailable to the Celtic boss because of injury. 

So far, the Hoops have not spent any money in the January transfer window, with Julian Araujo and Tomas Cvancara arriving on loan from Bournemouth and Borussia Monchengladbach, respectively. 

"We need to strengthen the squad, that's what we're trying to do. Whether we have anyone in for Sunday, I don't know," O'Neill told reporters.

"We are making strenuous efforts to improve the team. I think that we can do something. I know days are pressing; that's very, very obvious. I'm hopeful."

Asked if he would need a deeper squad to compete with the domestic and European demands, O'Neill conceded: "You are absolutely right.

"If we were lucky enough to get through, you're going to play at least a couple of games; there's no midweek break – that's the problem. You do need a proper squad for that.

"Not that it was something that was discussed after the game in Bologna, but I thought with the red card in the game at Hearts, we stuck it out. But they were out on their feet."

Celtic have won their last two major European matches against Dutch opponents, both times beating Feyenoord (in December 2023 and November 2025).

O'Neill's side are 24th in the 36-team table, and standing between themselves and progression are Utrecht, who are winless in their last 10 away major European matches (D2 L8) since winning 4-0 at MSK Zilina in October 2003. 

Ron Jans' side have taken just one point from their seven league phase fixtures and have already been eliminated from the competition, but O'Neill warned his players not to underestimate their Eredivisie opponents. 

"We have to win the game. It's as simple as that. If we do win the game, we're through," O'Neill said.

"It's not as easy as that. I've had a look at them and, despite their recent record, these boys can play. 

"They're definitely a decent side, coming here with nothing to concern themselves. They're probably thinking, let's go out and enjoy it, and that's a danger in itself.

"They can play. You give them an opportunity, and they will cause you problems."