Gary Mackay-Steven signed a pre-contract agreement with Celtic in January 2015, with a view to joining the club in the summer, but he made the move to Paradise at the end of the winter transfer window, joining on the same day as Stuart Armstrong.
Mackay-Steven began his career with Ross County and moved to Liverpool in 2007. After two years with the Anfield side, he joined Fulham before returning to Scotland in January 2011, joining Airdrie United.
An impressive six-month spell there secured a move to Tannadice in the summer and he made his debut for Dundee United in a UEFA Europa League tie against Polish side, Slask Wroclaw.
He would go on to make a total of 131 appearances for the club, scoring 27 goals, including two against Celtic.
Mackay-Steven would make an immediate impact by scoring on his debut against Partick Thistle within the first minute of the match.
He has also gained full international honours for Scotland, making his debut in a friendly match against the United States at Hampden.