Boca Juniors left-back Fabra was ruled out of the 32-nation tournament in Russia after rupturing his left anterior cruciate ligament during training in Italy on Saturday, reports Xinhua news agency.
Diaz has 13 caps for Colombia including eight in World Cup qualifiers. He moved to Paraguay's Club Olimpia last year after five seasons with Atletico Nacional.
The 34-year-old joined the Cafeteros squad at their training camp in Carnago, northern Italy, on Sunday.
Jose Pekerman's team will begin their World Cup campaign against Japan on June 19 before also facing Poland and Senegal in Group H.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
