There was a line from Martin O’Neill’s media conference in Lisbon the other night which hinted at a growing frustration with Kasper Hogh.

Hogh, who had missed a sitter at the back post from only two yards out, was subbed off at half-time after a woeful first half which saw Celtic go 3-0 down against Benfica.

Now on a goal drought which stretches over two months, it was another night where Hogh, a club-record signing at £11million, didn’t cut the mustard.

O’Neill was asked afterwards whether there might have been any temptation to keep the Danish striker on the pitch just purely to try and get him a goal. A scuff, a deflection, one off his backside – any goal at all.

‘No, I think you have to earn the right to be on the pitch,’ came the response from O’Neill. Ouch. It hardly required the detective skills of Poirot to understand what O’Neill was getting at.

In fairness, he qualified it slightly by insisting that he has no long-term concerns over Hogh. In the fullness of time, there is a confidence that he will come good and score goals for Celtic.

But how long do they give it? Having spent top dollar to sign Hogh from Bodo/Glimt, how long can Celtic afford to wait on him to get his act together?

That’s one of the burning questions facing O’Neill as he prepares to lead his team into battle with Hearts once again at Parkhead this afternoon.

It was notable on Thursday night that Celtic were much-improved in Lisbon once Hogh had gone off the pitch.

O’Neill moved Camilo Duran to play through the middle as a striker, with Callum Osmand and Haissem Hassan playing on the wings.

Celtic looked far more of a threat, much more direct and quicker at the top end of the pitch. They created quite a few good chances beyond the one which Duran converted with a header.

None of this reflects overly well on Hogh, of course. He arrived with a big pricetag and big reputation, a striker who could score goals in the Champions League.

But his Celtic career has largely been a non-event so far. His only goals came in a bundle back at the start of the season in August courtesy of a first-half hat-trick against Kilmarnock at Rugby Park.

Celtic fans thought they had signed a worldie. But that game must be qualified in the sense that, at that point, Kilmarnock were all over the shop and conceding four and five every week.

That first-half display was potentially the worst 45 minutes of football any team will produce in the Premiership this season, particularly in defence. Hogh scored a series of tap-ins.

But the way he has consistently failed to deliver in big matches over these past couple of months now has to be a serious concern for Celtic.

The numbers are unforgiving. All in all, it’s three goals in 807 minutes of football. And none at all in over two months.

A big-money striker signed to score goals who is not scoring goals and not playing well. At Celtic, that is a problem that quickly grows teeth.

Unsurprisingly, those close to Hogh are quick to defend him. His team-mates still speak of a player with a big character and bucketloads of ability.

‘Kasper’s a great guy,’ said Callum Osmand, who was impressive when he came off the bench against Benfica on Thursday night.

‘He knows how to act and how to hold himself and he’s a top professional. I don’t think I’ve ever seen him put a bad thing in his body, but, yeah, he knows what he’s doing.

‘Obviously his goals speak for themselves at Bodo and I’m sure it will come. He’s a top player. I see him every day in training and, yeah, he’s a really, really great guy, top player.

‘So, yeah, I’m sure it will come. He’s a really, really top player. I think he maybe just needs one to go in.

‘I think it is a lot about confidence, the attacking positions, and when your confidence is high, you play better and sometimes it’s about getting that goal, but he’s obviously a top professional.

‘He knows what he’s doing and I’m sure it will come. He’s been in the game for a long time and he’ll know better than me.’

For those who watched Hogh in the Champions League over the past couple of seasons, there is no question that he is a player of good pedigree and ability.

But the basic reality is that he is not showing it for Celtic. Patience, for all his ability and his pricetag, is not infinite.

Celtic need him to step up and start delivering in big matches, something which he has fundamentally failed to do so far.

There is a very good case to be made for O’Neill benching Hogh for Sunday afternoon’s clash with Hearts at Parkhead.

If that were to happen, it would be the clearest signal yet that patience is starting to wear thin with the Danish striker.

Would it be a shock if O’Neill started Duran through the middle and told Hogh to wait his turn on the bench?

Not really. The half-time substitution in Portugal already felt like a statement.

Hogh is 25 years old. He is not a young kid. And nor is he a project player. He was signed for the here and now.

He has the physical tools and the pedigree. But Celtic do not buy record signings to show glimpses and then go quiet.

They buy them to lead the line and put the ball in the net with the regularity that wins titles and keeps European campaigns alive. The clock is ticking louder than ever.

Another barren afternoon against Hearts and the conversation will shift again. It won’t be long until Hogh’s name has the word dud attached to it.

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