Sunderland boss Paolo Di Canio has been busy in the transfer market this summer having brought in nine new faces and it means he could be forced to trim his squad on Wearside.
The news has alerted Premier League sides to Gardner's possible availability with the 26-year-old a proven performer having racked up over 150 top-flight appearances during his time at Aston Villa, Birmingham and Sunderland.
Gardner was one of Sunderland's shining lights last season in a disappointing campaign, impressing after being used as an emergency right-back for a large period of the campaign.
Despite being played in a full-back position, the 26-year-old managed to score eight goals in all competitions last season for Sunderland
The former England Under 21 international's versatility and experience makes him an attractive proposition for clubs with his suitors now monitoring his situation at the Stadium of Light.