Olyroo Genreau had an impressive loan spell in the Eredivisie last season at PEC Zwolle, making 10 league appearances.
But the 21-year-old has struggled to gain traction under Frenchman Erik Mombaerts since his return, making just six appearances before the COVID-19 lockdown.
It’s understood Genreau - who in January helped Australia qualify for next year’s rescheduled Olympic Games in Tokyo - has agreed terms on a three-year deal.
Also heading to Campbelltown in Sydney’s south-west is 20-year-old winger Najjar, who is believed to be joining the Bulls on a season-long loan.
The former Western Sydney Wanderers junior has yet to play an A-League match, having signed a two-year pro deal last September.
The Bulls claim to have nailed down nine players ahead of their first training session on September 1 but have only announced former Socceroo Tommy Oar as their inaugural marquee.
They have been forced to delay confirming their roster due to the financial and scheduling issues resulting from the coronavirus.
However, Bosnian-based Australian defender Aleksandar Jovanovic, Brisbane Roar right-back Jake McGing and former Central Coast Mariners midfielder Liam Rose are also expected to join Ante Milicic’s squad.
Macarthur could also be the new home of fringe Socceroos keeper Adam Federici, who is off-contract at Stoke City where he’s dropped to third in the pecking order.
Central Coast gloveman Mark Birighitti has also been linked with the Bulls, but the Mariners are hopeful he will resign with them.