Munster wing Calvin Nash filled the number 14 jersey when Hansen missed out against Scotland in round two, while all of Osborne’s previous Test starts have come at full-back.
The 23-year-old has came off the bench to play in the midfield for Ireland, and also appeared for his province Leinster on the left wing.
Saturday, however, will be his professional start at right wing.
Having named a 6-2 split on the bench, Easterby cited Osborne’s ability to play across the backline should injuries occur as something that worked in his favour.
“So we’ve got a bit of flexibility there in terms of his positioning, a flexibility to move him around a little bit in certain parts of the field so we can utilise his left [foot], but he’s also got a right foot as well.
“So there’s a bit of flexibility within the system that would allow us to utilise him and Hugo in different positions.
“Sometimes there’s really tight calls and it’s just the gut, but in this case there’s a couple of reasons for that and one of those is that Jamie offers us more flexibility in the positions he can play.”
