The Supreme Personality of Godhead is known as all-powerful because no one can excel Him in any activity. In Bhagavad-gita (7.7) the Lord says, mattah parataram nanyat kincid asti dhananjaya: O conqueror of wealth, there is no truth superior to Me. No one can equal the Lord or be greater than Him, for He is the master of everyone. As stated in Caitanya-caritamrta (Adi 5.142), ekale isvara krsna, ara saba bhrtya. The Supreme Personality of Godhead, Krsna, is the only master of everyone, including even Lord Siva, what to speak of others. Lord Siva was already aware of the supreme power of Lord Visnu, but when he was actually put into bewilderment, he felt proud to have such an exalted master.