SCOTLAND's weakened squad has been warned to prepare for an immediate "onslaught" from group co-leaders Croatia in tomorrow's World Cup qualifier in Zagreb.

As another defender was lost from the heavily depleted Scotland squad – Gordon Greer became the seventh player to withdraw from the original group – the party which flew into the Croatian capital yesterday afternoon was told what to expect in the Maksimir Stadium.

Although Croatia have backtracked a little after earlier claiming they would boost their goal difference with a heavy defeat of the Scots, even boasting they would not allow Gordon Strachan's players out of their own half, the Scotland management team recognise that there is likely to be a bombardment straight from kick-off.

James Morrison will captain the team for the first time, the first English-born player to lead Scotland since Bruce Rioch against Holland at the 1978 World Cup. Darren Fletcher, Gary Caldwell and Scott Brown would all normally have been ahead of him in the list of probable captains but they are absent. "James has been an excellent Scotland player over a number of years now," said Strachan last night, ahead of Morrison's 27th cap. "He thoroughly deserves this recognition and honour after a terrific season."

However, the real interest lies in defence. Norwich City's Russell Martin, who normally plays at right-back at club level, and Andy Webster are the likely central defensive partnership with Grant Hanley the only other recognised centre-half in the squad. Greer reluctantly joined Brown, Gary Caldwell, James Forrest, Danny Fox, Lee Wallace and Liam Bridcutt by dropping out of the squad originally picked by Strachan.

Croatia and Belgium are joint leaders of Group A, on 16 points to Scotland's two. "Gordon has not defined exactly how we will set off in terms of attack," said assistant manager Mark McGhee. "We have spoken more about how we contain the onslaught that we expect from them early on but that requires us to hit the other way. It requires us to punch back. We can't just keep taking punches because, eventually against opposition like this, you will take a knockout punch.

"We know what to expect and we have worked on ways both physically, with our shape, and also mentally. We have tried to persuade the players that even with that onslaught they have to be prepared to stay calm and pass the ball and work their way out, and then we do have people who can go in the other direction. It's about striking that balance between the two [defending and counterattacking] and we've worked hard to achieve that this week. We feel content that, on paper and on the training ground, we have an opportunity to do that and now we've got to go and do the job."

Scotland were fortunate to lose only 2-0 against Belgium in Brussels in October, and Croatia in Zagreb are just as formidable. "I think they are just as strong," said McGhee. "They are different slightly. Technically, Belgium play a more sophisticated game. I think Croatia show the best of British elements: they are strong physically, tactically, they are very solid, and they are consistent in their team selection.

"They have a big centre-forward and then a smaller forward, whether it is Eduardo or whoever, playing off him. They have midfield players who can pass it and they have midfield players who can defend, they have full backs who can go forward, and they have centre-halves who are big, strong and quick. They have a decent goalkeeper. They have great balance in the team."

McGhee was unconcerned by the reported cockiness of Croatia coach Igor Stimac and striker Ivica Olic about their probable victory tomorrow. "I think they have back-pedalled. We are not going to take offence. We know they are a good side and will come at us full pelt; we have to be prepared for that. Given their record, they are quite entitled to believe they can beat us. We have to prove them wrong."

Greer had the desperate disappointment of having to pull out having been given his first senior call-up at the age of 32. Brighton & Hove Albion's medical staff had assured Scotland he would be fine to play after knee surgery but there was swelling when he trained this week and he was advised to withdraw. "Gordon is gutted," said McGhee. "He was desperate for the opportunity. We can't do anything about it, it's done."

Hanley, pictured, has trained normally again after a minor ankle injury and Shaun Maloney is also fine after a slight worry earlier in the week.