"Saul came on an made the most of his pace to score a great hat-trick.
"It has left us in control but we can't be too complacent. We have to finish the job in the second leg. They will be looking to shock us so we must be aware."
Meanwhile, Maccabi Manchester Yellow caused a major upset in the Harold Feldman Trophy by dumping out Haroldeans.
The form book was ripped up as they sealed an extra-time win and will now face MJSL champions Leeds Maccabi in the final.
The Merseysiders were on course to reach Oldham's Boundary Park when Jamie Harris netted.
But Richard Caplan struck back before Aaron Englander hammered home the 114th-minute winner.
To cap a miserable day for Haroldeans, Jonny Harris picked up two bookings and was given his marching orders.