Points leader Osby fastest in SX2 category inside Marvel Stadium.
Current SX1 points leader Luke Clout has topped qualifying at the 2019 Monster Energy AUS-X Open Melbourne for round five of the Australian Supercross Championship.
The CDR Yamaha Monster Energy rider set the pace with a 43.984s time inside Marvel Stadium, edging out rival and three-time defending champion Justin Brayton (Penrite Honda Racing), who set a 44.111s.
Visiting American Jason Anderson (Rockstar Energy Husqvarna Factory Racing) was third fastest following a best-lap of 44.536s, while CDR Yamaha Monster Energy duo Dan Reardon and Josh Hill were fourth and fifth respectively.
The top 10 was rounded out by Brett Metcalfe (Penrite Honda Racing), Dylan Long (Empire Kawasaki), Lawson Bopping (Empire Kawasaki), Richie Evans (Yamalube Yamaha Racing), and Jackson Richardson (Honda), who was the only rider from the unseeded session inside the top 10.
In the SX2 category, red-plate Josh Osby (Raceline KTM Thor) emerged fastest after setting a 44.674s, as fellow American Chris Blose (Penrite Honda Racing) was a fraction off, recording a fast-time of 44.866s.
Defending champion Jay Wilson (Yamalube Yamaha Racing) lodged a 45.469s time for third, followed by Aaron Tanti (Serco Yamaha) and Mitchell Oldenburg (Penrite Honda Racing).
Making his professional debut, Jett Lawrence (Geico Honda) was sixth ahead of Kyle Webster (Penrite Pirelli CRF Honda Racing), Dylan Wills (Davey Motorsports KTM), Geran Stapleton (Honda) and Darian Sanayei (Kawasaki).
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