Umar joined Roma in 2015 but has found regular playing time hard to come by at the Stadio Olimpico.
The 22-year-old spent the second half of the 2018-19 season at Serie B club Perugia where he scored three goals in 18 matches after failing to establish himself at Rangers.
Partizan will be the sixth club Umar is joining temporarily from Roma and but the Serbian team have the option to make the deal permanent at the end of the season.
📷 Umar Sadiq in Belgrade yesterday.— Partizan Belgrade 🇬🇧 (@FKPartizanEN) July 3, 2019
The Nigerian striker is joining the team in Slovenia after sealing a one-year, €100,000 loan move from @ASRomaEN.
The 22-year-old was on loan at Perugia last season. pic.twitter.com/jufJ8T5gsB
The 2016 Olympic bronze medallist completed the loan move in Belgrade on Wednesday and he is expected to join the rest of Savo Milosevic's team at their pre-season training camp in Slovenia.