The award-winning Irish author Colum McCann is recovering at his home in New York after he was assaulted in an attack on Saturday night.
The attack happened in New Haven, Connecticut, where the author was visiting ahead of delivering a keynote speech at a local university.
A man and a woman were involved in a dispute on a street in the city at around 10pm.
Mr McCann is understood to have intervened to assist the woman, and the man then punched him in the face.
He suffered significant facial injuries but he is expected to make a full recovery.
New Haven police have said they have "significant leads" in the case and are "hopeful of an arrest sooner rather than later".
It is understood they know the attacker's identity but not his whereabouts.
Detectives are due to interview Mr McCann again later today.
He is the author of six novels but is best known for his 2009 novel 'Let the Great World Spin'.
He was in New Haven to speak at the Southern Connecticut State University with a teacher from Newtown High School where students have been studying the book to deal with their grief following the shooting at the nearby Sandy Hook elementary school in December 2012.