Published Thursday, 05 June 2014
The House of Cards star is in the midst of a two-and-a-half week run at The Old Vic theatre in London.
On Wednesday, Spacey's improvisation skills were put to the test when a ring tone interrupted him during a passionate scene in which his character is on trial.
Spacey was addressing the audience with a plea for his innocence, when a mobile phone began ringing in that section.
The audience member attempted to ignore the call, prompting Spacey, who remained in character, to blurt out: "If you don't answer that, I will!"
His speedy response sparked a round of applause from the crowd.
The production marks the third time Spacey has played the lawyer and civil rights hero. He took on the one-man play in celebration of his decade-long stint as the artistic director of The Old Vic.
The actor will step down from the position next autumn and will be replaced by director Matthew Warchus.