Goalscorer Petric had an incident-filled game after replacing the injured Bryan Ruiz after an hour.
The Croatia international almost equalised with his first touch before finding the back of the net two minutes later after Damien Duff beat the offside trap to provide the assist.
Petric then required treatment on a wound suffered when scoring the goal and was off the field as Sunderland regained the lead.
"It was a hard game for us because it started very badly with the red card for Brede," Petric said. "Then we were 1-0 down so it was good to come back and equalise, although they scored two minutes after my goal which was a pity.
"I got a kick on my calf when I scored.
"It made a cut so I had to come off to have stitches put in and then by the time I got back on the pitch it was 2-1. It was a bit painful but I had injections so it was okay."