The avatars of Vishnu from current Mahayuga i.e., twenty eighth Mahayuga of Vaivasvata Manvantara are as follows:
Krishna Dwaipayana Vyasa (From Dwapara Yuga)
In the twenty-eighth Dvápara Yuga, the lord had his eighth incarnation as Vedavyãsa. He was born of Parashara with Jatukarnya as his preceptor. [Brahmanada Purana Upodhagata Parva Chapter 73 verse 92]
Bala rama (From Dwapara Yuga)
While listing 24 important incarnations, the sages list Krishna and Balarama as incarnations which happened in the Dwapara Yuga.
In the nineteenth and twentieth incarnations, the Lord advented Himself as Lord Balarāma and Lord Kṛṣṇa in the family of Vṛṣṇi [the Yadu dynasty], and by so doing He removed the burden of the world. [Śrīmad-Bhāgavatam first skandha chapter 3 verse 23]
Krishna (From Dwapara Yuga)
Buddha (In the Kali Yuga)
Then, in the beginning of Kali-yuga, the Lord will appear as Lord Buddha, the son of Añjanā, in the province of Gayā, just for the purpose of deluding those who are envious of the faithful theist. [Śrīmad-Bhāgavatam first skandha chapter 3 verse 24]
Kalki (At the junction (sandhi) of the Kali Yuga and the beginning of the next Satya Yuga)
In this Kali Yuga itself, when the junction period is yet to lapse, the lord will be born under the name of Kalki and Viṣṇu Yaśā. He will be born in the family of Parashara and have great exploits. [Brahmanda Purana Upodhgata Parva Chapter 73 verse 104].