The league leaders dominated the early stages and took a deserved lead when Sami Allagui slotted home from Adrian Ramos' pass, but the struggling hosts levelled proceedings in the second half as former SV Werder Bremen youngster Lennart Thy beat the offside trap to collect Fin Bartels' pass and fire through the legs of Hertha keeper Thomas Kraft.
The equaliser galvanised St. Pauli, who were desperately unlucky when Daniel Ginczek smacked against the bar. However, the on-loan Borussia Dortmund forward soon made good on his threat, albeit from the spot, to turn the tables in favour of the hosts.
However, with just two minutes remaining Ronny restored parity with a wonderful strike, his 17th of the season, from outside the box, before Sandro Wagner then volleyed in at the death to take the club from the capital four points clear of second-placed Braunschweig at the top. St. Pauli, meanwhile, remain just five above the drop zone.
Line-ups and statistics