One-nil down, Arsenal brought on the 18-year-old of Ghanaian descent for Reiss Nelson in the 85th minute.
And what an impact he had as he netted the equalizer with his first touch just 15 seconds after being on the pitch before netting the winner in extra time.
"[That sudden rush of attention] is quite hard to deal with," Bellerin explained in an interview on his club's official website.
"The best way to do it is to think that this is just the start.
"Some people think that it is the end but it is the other way around.
"It is just the start of your professional career and you have to handle it properly and realise that it is not always like that.
“There will be ups and downs. It is important that you keep humble, keep working hard and see it as the first step on a long journey.”
Nketiah has earned high recognition following his League Cup exploit with many taking to social media to sing his adulation while comparing him with Arsenal great Thierry Henry.
"I went down to the dressing room [after the game] and he was on his phone and he must have got messages from friends and on social media," Bellerin said.
"It must be quite hard in the first moments to [deal with that]."