The Dortmund defender was in and out of Thomas Tuchel’s first-team last season as BVB finished in second place in the Bundesliga table behind Bayern Munich.
Subotic worked with current Liverpool manager Jurgen Klopp during the 48-year-old’s eight-year spell in charge at the Westfalenstadion.
Klopp has already agreed a deal to sign Schalke defender Joel Matip in the summer transfer window but the Liverpool manager is thought to be keen to strengthen his options further.
And Subtoic’s future at Dortmund appears to be far from certain after the centre-half revealed that he is seeking talks with the German club over his long-term future.
“I have been a footballer for a decade. This was the first one in which I had very little playing time,” Subotic is quoted as saying by ESPN.
“My demands on myself are higher, of course. I did not become a footballer to earn my money on the bench. I want to play. I think if you know anything about me, you’ll know I’m a fighter.”
Subotic made just six Bundesliga appearances for Dortmund last season amid speculation linking the defender with an imminent move to the Merseyside outfit.
Liverpool finished in eighth place in the Premier League table.
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