The Belarusian enjoyed a successful spell at Arsenal before leaving North London to join Barca in 2008 for £15million.
The 30-year-old has since spent time on loan with Stuttgart, Wolfsburg and Birmingham City but has struggled to make an impact.
With the Spanish giants willing to terminate his contract, it has put Liverpool and QPR on red alert.
New Queens Park Rangers boss, Mark Hughes is determined to keep his side in the top flight and will spend heavily to do so.
Carling Cup finalists Liverpool are also keen to add the creative player to their squad.
Source: DSG