Dundee United midfielder Stuart Armstrong is wanted by Portuguese side Sporting Lisbon.
Celtic had been linked with the 22-year-old this week, yet now The Mail report they have competition.
Sporting signed Armstrong's former teammate in the summer, teenager Ryan Gauld, who had broken into the first team at Tannadice.
Gauld is so highly rated by the Primeira Liga side that they inserted a £48 million release clause into his contract, aware that they beat competition from Arsenal and Manchester United for his signature.
Armstrong has 17 goals and 26 assists in 141 games for Dundee United in his career so far, and has been a regular for Scotland's under-21 side.
He has a contract running until 2016 so United are under no immediate pressure to sell, but Celtic are said to have been scouting him in recent weeks ahead of making a move in the transfer window.
Sporting's interest is only likely to make Celtic intensify their efforts to land the central midfielder, but with United only four points below the Glasgow side in the SPL table, they may consider their own ambitions of a loftier priority than a short-term financial gain, for this January at least.