Oakland Raiders rookie left tackle Menelik Watson underwent arthroscopic knee surgery on his lateral meniscus last week and is expected to be sidelined one month, a source told ESPN NFL Insider Adam Schefter.
The Raiders are likely to continue to start Khalif Barnes at left tackle and Tony Pashos on the right side. Barnes had moved from right tackle to left tackle because of injuries to starter Jared Veldheer and Watson, his replacement.
Watson was a second-round pick of the Raiders in April (42nd overall). He suffered the injury last week in practice.
A right tackle by trade -- he has played only two years of organized football, one year at Florida State and one in junior college -- Watson moved to left tackle for the Raiders after Veldheer tore his triceps in training camp. Veldheer has been placed on injured reserve with a designation to return.
Barnes, a second-round draft pick by the Jacksonville Jaguars in 2005, started 57 of his 60 games with the Jags at left tackle before he joined the Raiders in 2009. He and Pashos were teammates with Jacksonville for two seasons (2007-08).
ESPN NFL Insider Adam Schefter and ESPN.com Raiders reporter Paul Gutierrez contributed to this report.