Ireland showed fight in the second half against South Africa despite an ill-disciplined first half which left them with 12 players on the pitch at one stage.
The world champions had just too much, though, and came away with a first victory in Dublin since 2012.
Farrell says the only way to close the gap on Rassie Erasmus’ side and others above them in the rankings is to show improvements in their Six Nations opener against France in three months’ time.
“We have a Six Nations which is our bread and butter, which matters the world to us,” Farrell added.
“So, [it’s about] how we go about the next nine weeks in our preparation individually and collectively as a team whilst everyone goes back to the provinces and coming back ready for international rugby, which was obviously difficult to do at the start of this campaign.
“But nine weeks to see how we need to come back into camp is plainly obvious after playing a game like that.”
Farrell is hoping that the likes of Brian Gleeson, Edwin Edogbo and Cormac Izuchukwu will be back fit and firing for their provinces as he looks to expand Ireland’s depth chart as they aim to regain their championship crown from France.
“There’s going to be more experience that has to be given to certain people if they show good form in the in the next nine weeks, so it’s staying across all that,” he said.