It is known that Bhimasena laughed at Duryodhana in Mayasabha due to the incident of Duryodhana falling down due to confusion.
Did it happen in front of Sri Krishna?
The following passage from Adi Parva of the Mahabharata confirms that it happened infront of Krishna
Yudhishthira, after having, through the wise counsels of Vasudeva and by the valour of Bhimasena and Arjuna, slain Jarasandha (the king of Magadha) and the proud Chaidya, acquired the right to perform the grand sacrifice of Rajasuya abounding in provisions and offering and fraught with transcendent merits. And Duryodhana came to this sacrifice; and when he beheld the vast wealth of the Pandavas scattered all around, the offerings, the precious stones, gold and jewels; the wealth in cows, elephants, and horses; the curious textures, garments, and mantles; the precious shawls and furs and carpets made of the skin of the Ranku; he was filled with envy and became exceedingly displeased. And when he beheld the hall of assembly elegantly constructed by Maya (the Asura architect) after the fashion of a celestial court, he was inflamed with rage. And having started in confusion at certain architectural deceptions within this building, he was derided by Bhimasena in the presence of Vasudeva, like one of mean descent.
But I heard from some other sources that it happened in the absence of Krishna (After krishna went to Dwaraka after Rajasuya).
Which one is true?