The severity of right-hander Carter Capps's elbow injury, however, is still unclear.
Capps will seek a second opinion on an elbow sprain that sent him to the disabled list Tuesday. Capps has pitched in nine games in relief and already has been ruled out at least a month.
The news was better for Alvarez, who was examined by a doctor and played catch Friday. He is to throw a bullpen session Saturday. Barring a setback, he'll start Tuesday against Tampa Bay following an extra day of rest.
Right-hander Randy Wolf will start Monday against the Rays.
The Associated Press contributed to this report.