Tuesday 20 January 2015 13:30, UK
Celtic have made an official approach to Dundee United for midfielder Stuart Armstrong, according to Sky sources.
Discussions regarding a fee are ongoing for the 22-year-old, who has 18 months remaining on his contract at Tannadice.
Celtic have already secured the services of Armstrong's team-mate Gary Mackay-Steven, who will move to Parkhead in the summer after signing a pre-contract agreement last week.
Armstrong, who joined Dundee United from Inverness Caledonian Thistle in the summer of 2009, has scored four goals in 20 games for Scotland U21s.
