The midfielder's impressive recent form has not gone unnoticed and he could be set for a return to England, with Newcastle in danger of losing his services
Ruben Zadkovich is the subject of interest from Millwall, but the Newcastle Jets are determined to keep their captain.
Zadkovich, 27, travelled to meet with the English Championship club after the conclusion of the Socceroos' East Asian Cup campaign in South Korea last month.
The midfielder enjoyed a consistent 2012-13 A-League season, prompting interest from last term's surprise FA Cup semi-finalists.
Newcastle Jets chief executive Robbie Middleby confirmed the club had granted permission for their skipper to meet with the team managed by Steve Lomas, but said they are hopeful of keeping him at Hunter Stadium.
"Ruben was scheduled to have a week off following his commitments with the Socceroos," Middleby said.
"He asked for the opportunity to take up Millwall's offer of a visit during this time and we have accommodated that request.
"At this stage, we have not received any formal offer for Ruben and he remains a Newcastle Jets player."
"Ruben is our captain and a highly valued member of our squad and our preference is for him to stay at the club for the remainder of his contract.
"We're looking forward to having him back in Newcastle for pre-season training this week."
Zadkovich is no stranger to England; he was briefly on the books of Queens Park Rangers early in his career and made nine league appearances for Notts County in 2005, before later spending two injury hit years with Derby County between 2008 and 2010.