Longest marathon playing Mahjong

The longest marathon playing Mahjong is 33 hr 3 min 48.58 sec and was achieved by Oleg Petrov, Anton Khantimirov, Mark Efremov and Nickolay Demyanov (all Russia) in the exhibition center “Sibir” in Krasnoyarsk, Russia, on 14-16 December 2012.