Liedson is contemplating his international future following Portugal's exit from the World Cup.
Portugal have named Brazilian-born Liedson in their squad for their World Cup qualifiers with Denmark and Hungary.
Liedson has admitted his future is in the hands of Sporting as the chase for his signature intensifies.
Celtic are reported to be the latest side to show an interest in signing Liedson as a free agent.
Sporting Lisbon have insisted that they have no plans to sell striker Liedson.
Liedson has told skysports.com that he is confident Sporting Lisbon can see off Rangers in the Uefa Cup.
Roma remain on course to qualify from Group F after David Pizarro's late strike earned them a 2-2 draw in Sporting Lisbon.
Roma were 2-1 winners over Sporting Lisbon at the Stadio Olimpico in UEFA Champions League Group F.