SCOTLAND assistant manager Mark McGhee believes the loss of four players from the squad for the opening World Cup qualifier in Malta on Sunday serves only to open the door for others to make an impact.

Celtic duo Kieran Tierney and Leigh Griffiths, who has scored seven goals this season, withdrew from the squad on Tuesday along with Kevin McDonald and James McArthur while Rangers captain Lee Wallace and Hearts striker Tony Watt were drafted in.

McGhee, speaking at the Scots' Mar Hall base on the outskirts of Glasgow, said: "We have to make sure it is not a blow.

Read more: Gordon Strachan drafts in replacement as Leigh Griffiths and three others pull out of Malta gameGlasgow Times: Scotland assistant Mark McGhee, left, with manager Gordon Strachan, right.

"We have other people here who will step up.

"You pick what you think is the best squad for the occasion so clearly losing four immediately is disappointing but we have to ask the others to step up and it gives them the opportunity.

"It is disappointing for him (Griffiths) and it is disappointing for us.

"He started the season in tremendous form and we were excited about that so of course it is disappointing but there are others who will now get an opportunity."

Watt, 22, on loan at Hearts from Charlton, won his only cap to date as a second-half substitute in the 1-0 friendly win away to Czech Republic in March.

Motherwell boss McGhee said: "We have been big fans of Tony since we first saw him.

"We brought him in for a training camp in an early squad and he had certain issues at that time.

"I had a couple of conversations with Tony over the summer, quite long conversations and I reported back to Gordon (Strachan) that what I was hearing was responsible, mature, a sort of change.

"It is no surprise to me that he is doing well where he is now and he is at a level now where we can bring him in.

"He offers something a little bit different and we are delighted to have that type of player in the form he is in now."

The Scots will also have to face England, Lithuania, Slovakia and Slovenia as they seek to reach the finals of a major tournament for the first time since 1998.

McGhee admitted the anguish of watching the Euro 2016 finals in France where Scotland were the only British country not involved and is, like everyone involved in the Scots camp, driven to make the World Cup in Russia.

He said: "It was a painful summer, it really was.

"I did my best to enjoy the Euros and I did enjoy a lot of it but I was hugely jealous of other nations that were there and kept trying to superimpose us at our best on certain games and in certain situations and wondering what we might have achieved.

"I go away back to the Nigeria game at Fulham (friendly, 2014) and the supporters that night were just amazing.

"I said to Gordon (Strachan), 'imagine going to a finals with this lot?'

"We have sold 4,500 tickets for this game in Malta and it shows the commitment the supporters have so Gordon, myself, the staff and players are driven by that desire to deliver something for the supporters that all these generations have missed out on."