World No. 84 Federico Delbonis knocked out local favourite and No. 4 seed Dusan Lajovic 6-3, 2-6, 6-4 to reach the quarterfinals on Thursday at the Serbia Open.
The Argentine won the game against his Serbian counterpart in two hours and 21 minutes.
Delbonis will next face Taro Daniel after the Japanese rallied from a set down to topple seventh seed John Millman of Australia 3-6, 6-2, 6-3.
Elsewhere, Italian Gianluca Mager continued his good run of form by beating another Aussie, Alexei Popyrin, 7-5, 6-2. Mager converted four of his 11 break-point opportunities to advance in just under an hour and a half.
The Italian will next take on Aslan Karatsev. The No. 3 seed from Russia took on Aljaz Bedene of Slovenia in a real battle but came out on top 6-3, 4-6, 7-6(5) in the final match of the day. Karatsev sent down nine aces and had to save one match point to claim the victory.
All eyes will be on Center Court on Friday though, as Novak Djokovic takes on fellow Serbian Miomir Kecmanovic.