The 31-year-old started his professional career in Croatia with Dynamo Zagreb before moving to Arsenal in 2007.
After two injury-ravaged seasons in London he joined Shakhtar in 2010 -- scoring in UEFA Champions League action that season against the Gunners.
Nationalised for Croatia in 2002, he has won more than 60 caps for his adopted nation. But he barely featured in this year's FIFA World Cup™ in his native country - he did not come off the bench for the opening game against Brazil.
He has signed a deal through to December 2015, with Lancenet sports news web portal saying his salary would be performance-based owing to his injury-chequered career.