The Scottish giants have reportedly contacted Portland about the possibility of signing the 26-year-old Nigerian, but the MLS side are reluctant to let him leave.
The Nigerian striker has also been linked with the likes of Celtic, French side Saint-Etienne and Mexican giants Tigres.
Ibrox side and Scottish Premiership-bound Rangers are claimed to be interested in signing Fanendo Adi from the Portland Timbers in the summer transfer window.
The 25-year-old Nigerian has recently been linked with a move to Sehlhurst Park, but he may find it tough to obtain a work permit.
The Nigerian scored 18 goals in 39 league games last season to help the Timbers secure their first-ever MLS Cup title.
The 25-year-old Nigerian is reportedly on Celtic boss Ronny Deila's radar after helping guide the Timbers to the 2015 MLS Cup title with his goalscoring exploits.
Celtic are reportedly pursuing Portland Timbers hitman Fanendo Adi, as are Cardiff City.