The 25-year-old’s current contract is set to expire at the end of the season.
The Black Cats boss told the Sunday Mirror: “A few weeks ago he was knocking on my door. He wants to play. Now he’s played against Man City, Man United and Spain.
“That’s how it changes. He’s played very well and if (Kieran) Richardson is fit, it gives me a huge dilemma. It’s fantastic for Bardo, I’m really pleased.
“He’s grabbed his chance and done very well. He’s pushed us into a corner, if you’re talking about contracts, and said, ‘What are you going to do?’
“He’s got eight months left. If he keeps playing like he is at the moment, then he will get himself a new deal.”
