Portland Trail Blazers center Festus Ezeli had his left knee injected with a bone marrow aspirate concentrate and Orthovisc on Tuesday in Chicago, the team announced.

The injection, performed by Dr. Brian Cole, is intended to alleviate pain and improve function. The Blazers say Ezeli will be sidelined for six weeks.

Ezeli missed six weeks last season after undergoing arthroscopic surgery on his left knee in January. He missed the entire 2013-14 NBA season after undergoing surgery on his right knee to reinforce his MCL and PCL.

The Blazers signed Ezeli to a two-year $15 million contract in July. The second year is reportedly partially guaranteed.

Ezeli, 26, had played his entire four-year career with the Golden State Warriors, who selected him with the No. 30 overall selection of the 2012 NBA draft.

He could be ready for the second week of preseason games, if the six week timetable holds true.