This temple is about five kms from Naachiyar Koil on the way to Tiruvarur. The Moolavar is Sri Saranathan facing east and the Thaayar is Sri Saranayagi.
The legend is during the time of Pralaya; Brahma made a small pot and deposited all the Vedas in it. The mud for making the pot was taken from this place from a tank known as Sara Pushkarani. Once the seven sacred rivers were playing in this place in the form of seven ladies and at that time one Gandharva by name Vishwavas happened to cross this place and be bowed to these ladies. The ladies argued among themselves as to whom this Gandharva made his namaskaram.
After some time the Gandharva returned, and when asked he said the namaskaram was for Sri Ganga Devi. While the other rivers went away Cauvery was not satisfied, and started penance under the banyan tree, by sitting on fire during summer and in water during winter. Sri Maha Vishnu gave her darshan and said that she will be worshipped on par with Ganga at this place.
Lord Sri Vishnu gave darshan along with his 5 consorts namely, Sri Devi, Sri Bhuma Devi, Sri Neela Devi, Sri Mahatakshmi and Sara Nayaki, This is the only place out of the 108 Divya Deshams such a darshan was given. Since Lord Sri Vishnu came and gave darshan in the month of Thai (January) on Poosha nakshatram, it is believed that the planet Jupiter enters this temple tank known as Sara Pushkarani, and at that time a bath in this tank is considered as equal to Kumbakonam Mahamaha Snanam (Bath). While Mahamaham occur once in twelve years, this Sara Pushkarani Snanam occurs every year.
This is the only Vishnu Temple, where the 'Thai Poosam' festival is celebrated, but generally Thai Poosam is celebrated in 'Sri Murugan Temples'
Thiru Mangaiazhwar has sung in praise of this Lord. On the banks of this tank there is a small Shrine for Goddess Cauvery and also for Sri Anjaneyar.
Another legend is the Nayakar King of Tanjavur along with his ministers wanted to improve the temple of Sri Rajagopala Swamy at Mannargudi. For this purpose they transported cart loads of bricks. On the way one stone was taken away from each cart by the minister. When the king came to know of this he sought an explanation from the minister for this theft, whereupon the minister prayed to Lord Sri Vishnu who gave darshan in the form of Sri Rajagopala Swamy of Mannargudi at this place. This pleased the King and he donated large areas of land for this temple.