FC Zenit St. Petersburg appear to be trying to offload Serbian forward Danko Lazovic and midfielders Szabolcs Huszti and Alessandro Rosina, announcing they have been excluded from a pre-season training camp in Italy.
The club's third-choice goalkeeper Dmitry Borodin was also left out, the club said.
"All the four players were informed about this decision of the coaching board," a statement said.
The training camp starts June 15 in Toscana, Italy.
The club did not explicitly say it was putting the players up for sale.
Lazovich, Huszti and Rosina all have another year to go on their contracts.
Lazovich, 29, was the club's second-top scorer this season behind Alexander Kerzhakov, with 12 goals in 31 matches.
He joined Zenit from PSV Eindhoven in 2010, scoring a total of 21 goals in 71 appearances.
Huszti, also 29, has a record of 12 goals in 85 games, losing his place in the starting lineup by the end of season. He joined in 2009 from Hannover 96.
Rosina, 28, switched to Zenit from Torino in the same year to score nine times in 49 matches. He spent the first half of 2011 on a loan at Serie A side Cesena, where he scored once in 10 matches.
