The midfielder came off the bench to great affect in the Capital One Cup tie at the Lane.
Trailing 1-0 to the Championship leaders, Ryan curled into the top corner from 30 yards to equalise and kick-start a recovery that led to a 3-1 victory.
That cameo display and first senior goal convinced Mauricio Pochettino to throw Ryan in at the deep end for his Premier League debut in the North London derby. He responded with another fine performance and held onto his place for Sunday's win against Southampton.
Ryan's goal polled 59.1% of votes from fans on Facebook, Twitter and tottenhamhotspur,com.
Nacer Chadli's goal at the Emirates was runner-up with 22.4%.
SEPTEMBER GOAL OF THE MONTH - FULL RESULT
Ryan Mason vs Forest - 59.1%
Nacer Chadli vs Arsenal - 22.4%
Roberto Soldado vs Forest - 8.3%
Ryan Mason - U21s v Southampton - 6.1%
Harry Kane vs Forest - 4.1%
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