A queue at least 400m long had formed just outside the church's walls.
Over 2,000 worshippers eventually made it inside the church's cavernous hall and onto its sprawling grounds for the 4.30am mass.
Many more stood outside, behind its wrought-iron gates.
In normal times, the church could accommodate up to 10,000 devotees. But these are extraordinary times.
Across this predominantly Catholic archipelago, churches began holding pre-dawn masses - known here as the "misa de gallo" or "mass of the rooster" - in the run-up to Christmas.
The masses will be held for nine straight days from Wednesday (Dec 16), culminating with the midnight mass on Christmas Eve.