Björk was in attendance at Jay Z's show in Uniondale, N.Y. last night, which Hov slyly acknowledged by slipping the piano figure from her track "Pagan Poetry" into his set. You can watch the short video— taken by Björk herself!— below.

RELATED: The Original Tracklist For Jay Z's "Reasonable Doubt" Includes Three Unreleased Songs
RELATED: Jay Z Ranks His Own Albums From Best to Worst