The Hawks, desperate to keep alive their finals hopes, batted first and struggled to 4-41.
Julien Goodall intervened and scored a vital 30 to steer his side to a below par 108.
Matt Johnston continued his good form for Willetton with 4-46.
In reply, the Dragons lost consistent wickets to look beaten at 9-93.
Andrew Winton was outstanding for Mt Lawley with 6-60 but it wasn’t enough as Willetton’s last two got their side over the line.
Alex Hepburn (34no) and Aaron McCall (7no) guided the Dragons home in a last wicket partnership that proved the difference.
Willetton declared at 9-121, 13 runs ahead, with Mt Lawley 2-74 in reply at stumps, with an outright result likely this Saturday.