An own goal from Incheon defender Matej Jonjic gave Busan a 1-0 lead in the 14th minute before Lee Chun-soo equalised three minutes after the break and Kim Jin-hwan scored with 20 minutes left to give the visitors all three points.
The defeat left Busan second from bottom on eight points, three above basement dwellers Daejeon, after 11 games.
League data released on Monday showed attendances in the top flight K League Classic had risen from almost 7,800 per match last season to more than 9,000 this year.
But only 4,052 watched Sunday's game in Busan as interest dwindles in a side whose last league title came in 1997. For Busan's six home games this season, the average is 5,155 according to the data.
The day's other match saw Gwangju grind out a 0-0 draw with Pohang.
On Saturday, defending champions Jeonbuk maintained their eight-point lead at the top with a 2-1 win over Daejeon, while Suwon consolidated second by beating Jeju 1-0.

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