CC Ādi 5.147

advaita-ācārya-gosāñi sākṣāt īśvara
prabhu guru kari’ māne, tiṅho ta’ kiṅkara
Synonyms: 
advaita-ācārya — Advaita Ācārya; gosāñi — the Lord; sākṣāt īśvara — directly the Supreme Personality of Godhead; prabhu — Lord Śrī Caitanya Mahāprabhu; guru kari’ māne — accepts Him as His teacher; tiṅho ta’ kiṅkara — but He is the servant.
Translation: 
Lord Advaita Ācārya is directly the Supreme Personality of Godhead. Although Lord Caitanya accepts Him as His preceptor, Advaita Ācārya is a servant of the Lord.
Purport: 

Lord Caitanya always offered respects to Advaita Prabhu as He would to His father because Advaita was even older than His father; yet Advaita Prabhu always considered Himself a servant of Lord Caitanya. Śrī Advaita Prabhu and Īśvara Purī, Lord Caitanya’s spiritual master, were both disciples of Mādhavendra Purī, who was also the spiritual master of Nityānanda Prabhu. Thus Advaita Prabhu, as Lord Caitanya’s spiritual uncle, was always to be respected because one should respect one’s spiritual master’s Godbrothers as one respects one’s spiritual master. Because of all these considerations, Śrī Advaita Prabhu was superior to Lord Caitanya, yet Advaita Prabhu considered Himself Lord Caitanya’s subordinate.