It think it might be anthracnose disease caused by fungal pathogen Colletotrichum coccodes or Colletotrichum orbiculare.

To confirm the disease please slice off the lesion to see pale coloration of flesh underneath. Also the texture of flesh may appear granular. If possible please upload the image with sliced fruit.

Generally the main symptoms of anthracnose are appearance of brown small, circular, sunken lesions on ripen fruits at the initial stage. As the disease progress the lesions enlarge, appear more hollow with distinct circular rings. Under wet condition the lesions produce light pink colored spores.
This lesions may coalesce; leading to development of secondary saprophytic bacteria and rotting of whole fruit.

http://www.extension.umn.edu/garden/y...