While Lord Rama was returning to the village of Ayodhya after saving Sita, his wife, from the hands of Ravana, He was accompanied by Sugriva, Lord Hanuman and Vibishana who came to take part in his coronation ceremony. While he was returning Sri Ranganatha deity that he had received in the form of a gift from Rama, Vibishana reached the south. Admiring how beautiful Cauvery River, as well as the environment there was, he wished to rest for some time, there. What he did not know was that, Vinayaka was present there, he was in the avatar of a small boy, he told the him to guard the gift that he had recieved. While he was staying put for Vibishana, he put the diety on the earth and hid inside the mountain. The boy had disappeared, and he could not find him anywhere. He used all the strength he possessed to shift the deity from its place, but couldn't succeed. As a result of this, Lord Ranganatha, who was actually from Sri Lanka, had to abort his expedition and chose the village of Sri Rangam, in the form of his new home. When he saw him standing atop the mountain, Vibishana injured him, on his cranium the mark caused by the same, can be seen on the deity of Vinayaka even today. Hence, we know that Lord Vinayaka, as well as Lord Ranganatha who is also located close by is watching over us.