Former NRL star Daniel Vidot scored his first try for the United States as the Hawks over-powered South Africa 38-18 in Pretoria.
Vidot, who played 114 NRL matches for the Raiders, Dragons, Broncos and Titans, scored the opening try and performed strongly playing centre in his debut for the USA.
The 34-year-old moved to the United States in 2018 to pursue a career with the WWE and qualifies for the Hawks under International Rugby League's five-year residency rule.
He has previously played 10 Tests for Samoa, including the 2013 World Cup and 2014 Four Nations tournament, and was selected for the Hawks after playing for DC Cavalry in the USARL's north-east Rugby League United conference.
Former Toronto Wolfpack centre Ryan Burroughs, who spent a season with the Eels, and Wes Piggins, a nephew of Rabbitohs patriarch George Piggins, are other Hawks players with NRL links.
USA coach Sean Rutgerson played for Canberra and North Sydney Bears forward, while also representing South Africa at the 2000 World Cup.
Tries by Vidot, winger Andre Williams and second-rower Wes Piggins gave the Hawks an early 16-0 lead, but the Rhinos narrowed the deficit to 20-12 at halftime.
Williams finished with a hat-track, while hooker Mason McCrory, five-eighth Ryan Bannerot and interchange forward Derek Lipscomb also scored as the tourists ran out 38-18 winners.
The second Test between the USA and South Africa will be played on Saturday.