Hertha Berlin coach Felix Magath has backed midfielder Kevin-Prince Boateng to make the difference in the Bundesliga play-off second leg at SV Hamburg on Monday. Boateng was an unused substitute in the 1-0 home loss on Thursday with Hertha facing relegation if they fail to turn around the result. “I’m convinced that Prince can be a decisive factor in Hamburg, as well as for Hertha in the future,” Magath told the Bild website on Saturday. The 35-year-old has been used sparingly this season having returned to his boyhood club but Magath said there has been no row. “There is no issue. Prince and …