Doubts over the futures of Fernando Screpis and Anthony Basso have been raised after the pair were left out of Hearts' German training camp squad.
Striker Calum Elliot is also not among the 24 listed as he considers a loan move to Inverness Caley Thistle.
Goalkeeper Basso is replaced by Jamie MacDonald, who was on loan to Queen of the South last season.
Midfielder Screpis played as a trialist for Plymouth Argyle in their 2-2 draw with Kidderminister.
New Hearts manager Csaba Laszlo has set his sights on reducing the size of his squad and there were reports prior to his arrival of a contract dispute between Screpis and the Edinburgh club.
Argentine Screpis, who arrived via Kaunas, has made just five appearances for Hearts, while former Auxerre goalkeeper Basso has played just eight times.
Finnish striker Juho Makela will make the journey, joining his team-mates on Tuesday, following his loan spell with HJK Helsinki.
MY SPORT: DEBATEMakela has started just three games in two-and-a-half seasons at Tynecastle, but he has scored six goals in 12 games back in his homeland.
Several youngsters have been included in the provisional party, which sets off on Sunday, including defender Matej Rapnik and strikers David Templeton and Gary Glenn.
Hearts could also have Uganda midfielder David Obua on board soon after opening talks with the free agent, who left South African side Kaizer Chiefs earlier this year.
But defender Robbie Neilson will stay behind to work his fitness, while midfielders Bruno Aguiar and Mirsad Beslija are ruled out through injury.
Hearts will play three friendlies against German opposition, including Kaiserslautern.
Meanwhile, Caley Thistle say they are still waiting to hear from Hearts about Elliot and believe there are other clubs interested in his signature.
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