I wouldn't chance it if you can get a passport extension .
Maybe you can try contact Singapore immigration check point authority
ICA Call Centre
Tel: 6391 6100
24-hour automated answering service for information on our services and procedural requirements.
You may also wish to speak to our Customer Service Officers during the following periods, except Public Holidays:
Weekdays: 8.00 am to 5.00 pm
Saturdays: 8.00 am to 1.00 pm
and
AIR CHECKPOINTS
Changi Airport 24 Hours
Passenger Terminal Building II, P.O. Box 6,
S(918141) Tel: 6214 8427