Sven Helbig, (known for music production and remixing several Rammstein tracks) has stated on his Facebook page that he will play the piano on a track that is to be released on the Mein Herz Brennt single.
“On the next RAMMSTEIN single, I will play piano and Till Lindemann sings. I am not allowed to tell the name of the song yet :-)”
Sven Helbig has worked as a producer, composer and arranger with Rammstein, Pet Shop Boys, Snoop Dogg, Polarkreis 18, the Fauré Quartett, opera singer René Pape, German rapper Sido and numerous theater productions.
Source: facebook.com, thank you LittleLuckyLink