Keane has turned to the Bluebirds hotshot as his new No1 target after giving up on Preston marksman David Nugent.
The Western Mail understands Sunderland have already had an offer of £3m for the 23-year-old turned down by the Bluebirds. But sources in the north-east say Keane will up the stakes in the next few days as he continues building a squad capable of keeping Sunderland in the Premiership.
Keane has been back in touch with Cardiff and Chopra's agent this week and is so eager to sign the striker, he is prepared to test the Bluebirds' resolve with the higher offer.
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