rama rama maha-baho
na jane tava vikramam
jagati jagatah pate
[Goddess Yamuna said:] Rama, Rama, O mighty-armed one! I know nothing of Your prowess. With a single portion of Yourself You hold up the earth, O Lord of the universe.
The phrase ekamsena (“with a single portion”) refers to the Lord’s expansion as Sesa. This is confirmed by the acaryas.