Scotland manager George Burley has explained the three surprise call-ups to his squad for the friendly against Northern Ireland at Hampden on August 20.
Derby County winger Kris Commons, an Englishman who qualifies through his grandparents, is joined by Falkirk skipper Darren Barr, who is also named in the senior squad for the first time.
Preston defender Callum Davidson returns to the Scotland set-up at the age of 32 after six years in the wilderness.
On Commons, Burley said: 'I became aware that Kris could qualify for Scotland a few months ago. I saw a lot of him when I was manager of Derby and he was at Nottingham Forest.
'He transferred to Derby in the summer and I had him watched. I think he will give us a different dimension. He is a boy with a lot of ability, he is a naturally left-sided winger and maybe we have lacked width in the squad.
'I spoke to the boy and he was keen and enthusiastic to join the squad.'
Burley insists Barr and Davidson, who has been capped 17 times, bring a mixture of youth and experience to his squad for what will be the last friendly match before the 2010 World Cup qualifiers begin next month with a double-header against Macedonia and Iceland.
The Scotland boss said: 'Callum is an experienced player who has played for Scotland in the past. He did very well for Preston and I watched him in a pre-season game against Motherwell.
'He is fit and injury-free and this is an opportunity to look at him. Darren Barr is one for the future. He was involved with the B squad last year and he is still finding his way.
'But this was another good opportunity to bring a young player in.'
Scotland squad to play Northern Ireland in a friendly at Hampden on August 20:
Gordon (Sunderland), Marshall (Norwich City), McGregor (Rangers); Barr (Falkirk), Berra (Heart of Midlothian), Caldwell (Celtic), Davidson (Preston North End), McManus (Celtic), McNaughton (Cardiff City), Naysmith (Sheffield United), Whittaker (Rangers); Brown (Celtic), Commons (Derby County), Fletcher (Manchester United), Hartley (Celtic), Morrison (West Bromwich Albion), Rae (Cardiff City), Robson (Celtic), Thomson (Rangers); Boyd (Rangers), Clarkson (Motherwell), Fletcher (Hibernian), McFadden (Birmingham City), Miller (Rangers).
Scotland under-21 squad for UEFA Under 21 Championship qualifying match against Lithuania in Suduva, Marijampole on August 20:
MacDonald (Heart of Midlothian), McLean (St. Johnstone), Smith (St. Mirren); Caddis (Celtic), Considine (Aberdeen), Cuthbert (Celtic), Kenneth (Dundee United), Reynolds (Motherwell), Scobbie (Falkirk), Wallace (Heart of Midlothian); Arfield (Falkirk), Conroy (Celtic), McArthur (Hamilton Academical), McDonald (Burnley), Mulgrew (Aberdeen), Robertson (Dundee United), Stevenson (Hibernian); Campbell (Hibernian), Dorrans (West Bromwich Albion), Elliot (Heart of Midlothian), Lennon (Rangers). McCormack (Cardiff City).