Lopez sprained his knee in the second quarter of Phoenix's win over the Los Angeles Lakers Sunday night when teammate Jared Dudley fell into him while driving to the basket. An MRI revealed sprained medial collateral and posterior cruciate ligaments.
Lopez started the Suns' first nine games, but struggled while trying to recover from a back injury last season that damaged nerves in his right leg and hampered his explosiveness. He averaged 5.3 points and 4.3 rebounds while playing just 17 minutes per game.
Unsigned free agent Earl Barron has emerged as the most probable replacement for Lopez, sources close to the situation told ESPN.com senior NBA writer Marc Stein.
One source with knowledge of the Suns' thinking told Stein that the Barron signing is "likely."
Information from The Associated Press was used in this report.