The professional Iranian boxer defeated the Lithuanian boxer 3-2 in the lightweight.
Shahbakhsh will face Uzbekistan’s Abdumalik Khalokov on Wednesday.
He started the campaign with a 5-0 win over Gambian Musa Cham. Shahbakhsh also defeated Italian Gustavo Rivera in the second round with the same result.
The Iranian beat Kyrgyzstan’s Munarbek Seitbek Uulu 5-0 in the quarterfinals.
The gold winners at the showpiece will walk away with a prize money of $100,000.
The silver medalists are to be given $50,000, and both bronze-medalists will be awarded $25,000 each. The total prize purse stands at a whopping $2.6 million.
The competition is being held in Belgrade, Serbia from Oct. 27 to Nov. 5.