Boss Jim Magilton says he is considering whether to offer contracts to midfield trialists Alexis Bertin, Eugen Bopp and Colin Healy. All three played 45 minutes of the pre-season game at Boston.
Magilton told the club site: "We've had a look at them in training this week and during the game at Boston.
"I had some knowledge of the other two lads but Alexis was new to us and considering he has very limited English, he's done well.
"The lads are going home now and won't be with us next week but I'll be sitting down with Bryan Klug and the rest of the coaching staff and deciding where we go from here."
Healy is reported to have been offered a contract by SPL side Motherwell, while Bertin is understood to be spending next week on trial at Coventry City.
Magilton has also refuted Friday's report claiming the Blues were tracking Port Vale's Chris Birchall: "We have made no contact with anyone about the player."