Dr. Khalfayan has diagnosed a tear of the meniscus in Montero's left knee. Montero will undergo surgery on a to-be-determined date next week and is expected to miss approximately four to six weeks.
Montero, 23, was optioned to AAA Tacoma in the Pacific Coast League on May 22. In seven games with the Rainiers he was hitting .250 (7x28) with 3 doubles, 1 triple and 2 RBI. His last game was May 29 at Colorado Springs.
Montero hit .208 (21x101) with 6 runs scored, 1 double, 1 triple, 3 home runs and 9 RBI in 29 games with the Mariners this season. The Mariners were 15-10 in games when Montero started behind the plate.
Montero hit .206 in April (17 games), and was hitting .211 in May (12 games). His 3 home runs all came in Felix Hernandez starts, including a go-ahead solo blast May 8 at Pittsburgh off A.J. Burnett.