Koji Uehara has pitched well for the Boston Red Sox this season and is just one appearance away from having the 2014 option in his contract triggered.
Uehara has a 1.35 ERA, 12 saves and 74 strikeouts in 53 1/3 innings this year.
His one-year, $4.25 million deal included a $4.25 million vesting option for the 2014 season that becomes guaranteed when he pitches in 55 games, according to a source. Incentives can push the value of the deal to $5 million with 35 games finished.
Uehara has appeared in 54 games through Monday.