Rangers defender Borna Barisic
Barisic joined Rangers from Osijek in the summer transfer window for a fee reported by The Daily Mail to be worth £2 million.
The Croatia international has had injury issues, and Jelavic believes that Rangers will have a quality player on their hands when Barisic is fully fit.
Jelavic told The Scottish Sun about Barisic: "I know what kind of player you have on your hands. When Borna is fit, he is unstoppable. He is one of the modern left-backs and I expect him to be a big success."
Jelavic - who is now based in China and is playing for Guizhou Zhicheng - joined Everton from Rangers in January 2012 for a transfer fee reported by The Scottish Sun to be worth £5.5 million.
The 33-year-old former Croatia international was on the books of Rangers from 2010 until 2014.
Rangers are third in the Scottish Premiership table at the moment with 30 points from 15 matches, three points behind leaders and bitter Old Firm rivals Celtic.