The 19-year-old Talagi, who made a try-scoring debut by running through Tom Trbojevic against Manly last week in a 28-24 win, moves from centre to five-eighth for Easter Monday's meeting with Wests Tigers.
Dylan Brown will assume the No. 7 jersey vacated by Moses, who faces up to eight weeks out with a foot injury.
It's the latest sign of the courage of Moses, who played on against Manly and has previously pushed through the pain barrier of a broken eye socket and a hairline fracture in his back.
"For someone who started their NRL career and had people question their toughness and physicality, Mitch has become such a tough competitor over the past four or five years," said Eels back-rower Shaun Lane.
"He's developed his game so much, so the contrast between those early days, it's like he's a new man.
"If you have one of your leaders in your team competing like that, it sets the standard for the rest of the team.
"You might not be able to play injured, but you never give up."
Talagi will be expected to play with a similar amount of bravery after his impressive debut, which left captain Clint Gutherson thinking the Eels had unearthed another diamond in the rough.
"After the game he was sitting there like he had just played an SG Ball (under-19s) game, so nothing bothers him, everything's just at that same level," Gutherson said.
"He's similar to Dylan, he's relaxed and just laps it up and plays his game.
"Him playing more (at NRL level) is going to make him even more of a danger and more of a threat.
"Losing a halfback, no matter what team you are, it's always hard... Blaize and Dyl are going to do an extremely good job."
Talagi will line up against Wests Tigers five-eighth Lachlan Galvin, who was his halves partner at Westfields Sports High School this time last year.
The Eels have won 11 of the past 13 Easter Monday games between the two sides and will hope to be boosted by the inclusion of back-rower Bryce Cartwright, who is struggling with a rib issue.
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