Kṛṣṇa can become the director and spiritual master of anyone who is serious about getting the mercy of Kṛṣṇa. The Lord sends the spiritual master to train a devotee, and when the devotee is advanced, the Lord acts as the spiritual master within his heart.

teṣāṁ satata-yuktānāṁ bhajatāṁ prīti-pūrvakam dadāmi buddhi-yogaṁ taṁ yena mām upayānti te

“To those who are constantly devoted and worship Me with love, I give the understanding by which they can come to Me.” Kṛṣṇa does not become the direct spiritual master unless one is fully trained by His representative spiritual master. Therefore, as we have already discussed, the Lord’s representative spiritual master should not be considered an ordinary human being. The representative spiritual master never gives any false knowledge to his disciple, but only perfect knowledge. Thus he is the representative of Kṛṣṇa. Kṛṣṇa helps as the guru, or spiritual master, from within and from without. From without He helps the devotee as His representative, and from within He talks personally with the pure devotee and gives him instructions by which he may return home, back to Godhead.