Sydney jumped to a 3-0 lead through Mark Bridge, Adam Casey and Terry McFlynn - and Stuart Musialik had a chance to make it 4-0 midway through the second-half, but struck the crossbar from less than five yards.
The ever-competitive Simon than gave Mariners hope with a cool finish one-on-one with Sydney goalkeeper Ivan Necevski before Nick Mrdja turned home a cross to suddenly rattle the home defence.
The Mariners' fight-back was complete on 81 minutes when Simon leapt highest to bounce home a superb header to make it 3-3.
"It does feel like a victory, I must admit," Simon told Fox Sports at the final whistle. "It was a special comeback. We've shown tremendous character.
"I don't know what it is, it seems like we need three goals from the opposition to kick us into gear!"
Simon now sits clear at the top of the A-League scoring charts and he added: "I'm enjoying it and hope it continues. It's been another high scoring F3 derby. It's good to produce so many goals for the fans."