The Terrors are determined to keep another pair of talents away from Celtic.
Celtic have already begun planning for next season, with a rad on Dundee United again being mooted.
The club snapped up Gary Mackay-Steven and Stuart Armstrong from Tannadice in the winter transfer window and have recently been linked with another pair of the club's best players.
In December last year Celtic were first linked with a move for Dundee United forward Nadir Ciftci by the Scotsman.
In April the Daily Mail linked them with a move for both Ciftci and John Souttar.
The pair are two of the Terrors best players and Celtic are once again hoping to raid the club this transfer window.
Dundee United have now made steps to try and prevent this from happening. The BBC has reported that the club have offered the pair, whose current deals expire next summer, new contracts to stay at the club.
"Both players have proved their worth to the team and the club as a whole and merit the extension offer.
"We believe that Dundee United remains the best club for both players to develop and, as such, have made enhanced longer-term offers to the players that reflect their value to Dundee United."
Celtic are already being linked with several new signings, the Dundee United pair being just two of them.
Willem II defender Mitchell Dijks is also believed to be on their radar, as is Brescia midfielder Ahmad Benali.