Qualifier and current world No.95 Vukic recorded a 6-4 3-6 6-3 win over Bosnia-Herzegovina’s Damir Dzumhur in Tokyo on Thursday afternoon.
The Sydneysider fired down 12 aces to two during his one hour 52-minute triumph.
Vukic won 85 per cent of first-serve points and broke twice from his only two opportunities.
The 29-year-old will next face Germany’s Daniel Altmaier, a straight sets winner over seventh-seeded Canadian Denis Shapovalov.
Thompson, who along with Vukic played in the Davis Cup defeat to Belgium in Sydney earlier this month, went down in an opening-round epic that lasted three hours seven minutes.
After splitting the opening two sets, both tiebreakers, with Brandon Nakashima, the 24-year-old Californian came from behind to win 6-7 (6-8) 7-6 (7-4) 6-2.
World No.78 Thompson led the double fault count 5-1 and served 10 aces to match his opponent.
But the 31-year-old from Sydney ran out of steam, leaving Nakashima to set up a last-16 clash with Hungarian qualifier Marton Fucsovics, who upset eighth seed Frances Tiafoe on Wednesday.
In other results, Taylor Fritz progressed along with fellow Americans Sebastian Korda, Jenson Brooksby and Ethan Quinn.
Italy’s Luciano Darderi and Casper Ruud of Norway also moved on.
World No.1 and 2025 US Open winner Carlos Alcaraz opens his campaign later on Thursday night against Argentine Sebastian Baez.
AloJapan.com