Callum McGregor has warned that Celtic could suffer more damaging results unless they show a major improvement on the back of their Old Firm defeat to Rangers.Celtic were thrashed 3-0 at Ibrox on Sunday afternoon in the quarter-finals of the Premier Sports Cup. Manager Martin O’Neill claimed afterwards that the match should serve as a major wake-up call to his squad.It comes only a few weeks after they suffered a humiliating Champions League exit at the hands of LASK, a tie in which they blew a four-goal lead.In a scathing verdict, McGregor admitted that there was no fight in the Celtic team after losing the first goal against Rangers.With the sides due to meet again in the league next weekend, the Parkhead skipper believes more pain could be on the way unless he and his team-mates buck up their ideas.Asked whether he felt like a performance and result like this had been in the post, McGregor replied: ‘Yeah, I think I said that after LASK. Celtic skipper Callum McGregor struggles to comprehend the nature of Celtic’s Ibrox setback‘You can see it, 100 per cent. You can see it, especially for the guys that have been here for a long time and the guys that have been watching Celtic for a long time.‘You see the team and how it functions and how it performs and how it behaves. It’s just been too bitty.‘So we have to find a way to bring it back and bridge that gap and start to bring it together. Because if we don’t, then you’ll have more days like this.‘We were poor in pretty much every area of the game. Once we went behind, we never looked like we were recovering really to be honest. We never really looked like getting back in it.‘I’m not going to shy away from that because everyone will be talking about it. Let’s be fair. If we want to be a good Celtic team, then we have to win the big games.‘That’s one thing we’ve always done is win big games and turned up when it mattered. So far this season, we’ve been bitty in games and we need to fix it.’After Rangers midfielder Dan Neil scored his second goal of the game to make it 3-0 in the second half, McGregor could be seen saying to his team-mates: ‘No more goals’. McGregor insists his team lacked the fight to get back in the game after going behindThe skipper admitted that it eventually became an exercise in damage limitation against a Rangers team who were utterly dominant on the day.He also stressed the need for some of Celtic’s new signings to get up to speed and understand the demands of playing for the club.‘I think the difference between the two sides was you’ve seen a team — and then you’ve seen a team of individuals as well,’ he continued.‘Rangers were a team and you could see that. We looked like a team of individuals that wanted to do our own thing and play when we got the ball. Not necessarily run when you don’t have the ball.‘That’s the one thing you can’t do when you come here is just don’t run. You can’t defend with six players, it’s impossible. We’re trying to get the message to everyone that we have to be a team.‘You don’t want fours and fives for sure. As soon as the third goal went in, then I’m saying to Cam (Carter-Vickers) and Scalesy (Liam Scales): “Look, no more goals, we have to just tighten this up”.‘Of course, we always want to get back in the game. And we always want to be a team that, even at 3-0 down, you still want to have a chance. But you have to understand the circumstance you’re in as well. McGregor was seen imploring his team-mates to tighten up and not concede any more goals‘We have to be the team that we want to be. We need to find a way to do that quickly because we lost a big game in LASK. We lost another big game today and it’s not acceptable.‘There’ll be other big games throughout the season and eventually you have to win one if you want to be considered a good team.‘We’ve put ourselves under pressure. We need to respond on Thursday (against Ferencvaros) and we need to respond on Sunday. But we very quickly need to get to the level.‘There’s some new guys in and we’re trying to get them bedded in, trying to get them to understand the system, how we want the Celtic team to look.‘There’s been shades of it this season but not enough. So, eventually, the penny has to drop. We have to get there. Because you can’t just turn it on and off, it’s impossible.‘Like I said, it’s two big games that we’ve lost. And you probably won’t get many more before the pressure really ramps up. We have to be honest about that and not shy away from it. We have to fix it.’