There is no doubt about Lord Kṛṣṇa’s being the Supreme Lord. Otherwise, how was it possible for Him to kill a giant demon like Pūtanā when He was just on the lap of His mother, to overturn a cart with His leg when He was only three months old, or to uproot a pair of arjuna trees so high that they touched the sky, when He was only crawling? All these activities are impossible for anyone other than the Lord Himself.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
तोकेन जीवहरणं यदुलूकिकायाः त्रैमासिकस्य च पदा शकटोऽपवृत्तः । यद्रिङ्गतान्तरगतेन दिविस्पृशोर्वा उन्मूलनं त्वितरथार्जुनयोर्न भाव्यम्
tokena jīvaharaṇaṃ yadulūkikāyāḥ traimāsikasya ca padā śakaṭo'pavṛttaḥ | yadriṅgatāntaragatena divispṛśorvā unmūlanaṃ tvitarathārjunayorna bhāvyam
SB 2.7.27