Arzani's impressive performances in the A-League last season earned him a place in the Socceroos squad for the 2018 FIFA World Cup – where he came off the bench in all three games for Bert van Marwijk's side – and a move to Melbourne City's parent club Manchester City.
He then joined Celtic on loan where an ACL injury will keep him out for the rest of the season, but Brattan claims Najjarine could become a more complete player than the Iran-born star.
"When I first came here and saw those two, Ramy was a more complete player," Brattan said.
"He's a two-way player. He gets back and defends as well which is fantastic and we need that in our team.
"Last year I carried Daniel a fair bit on that right side but he gave us our rewards going forward.
"Hopefully Ramy can step into that position and make it his own, produce some quality football.
"If he plays regular football and takes his opportunities like he did on the weekend, he's going to go a long way."
Najjarine impressed in his third substitute appearance of the season against Adelaide United on the weekend after replacing the injured Ritchie De Laet after just 23 minutes.
