A priceless 1929 painting "Woman in a Red Armchair" by Pablo Picasso was vandalised by a man who spray-painted on it at an art museum in Houston, US.
The man was seen on a surveillance camera at the Menil Collection, reports said.
The act was also captured by a bystander with a smartphone camera and later posted online.
Museum officials discovered the damaged artwork almost immediately and rushed the painting -- with the spray paint barely dry -- to the museum's conservation lab, where repair work has started.
The repair went well and most of the damage had been fixed, officials said.
The vandalised painting is one of nine by Picasso owned by the museum.