The Boston Red Sox placed reliever Keith Foulke on the 15-day disabled list on Wednesday with a left knee injury that will require arthroscopic surgery. Foulke will undergo the procedure on Thursday. He was sent from Arlington to Boston on Tuesday to have an MRI on his ailing knee, which has caused the righthander problems most of the season. Foulke suffered his second blown save in a week when he gave up two ninth- inning runs in a loss against the Rangers on Monday. He is just 5-5 with 15 saves, four blown saves and a lofty 6.23 ERA this season. Last year, Foulke had 32 saves and was a key contributor to the team's championship run. He closed out all four games in a sweep of the St. Louis Cardinals in the Red Sox' first World Series title in 86 years. To replace Foulke on the active roster, the Red Sox purchased the contract of pitcher Scott Cassidy from Triple-A Pawtucket. Mike Timlin is expected to fill in as the Red Sox closer. He picked up his second save of the season in a 7-4 win over the Rangers on Tuesday. The Red Sox could also have Curt Schilling helping them in the bullpen after he completes a minor league rehab stint. Schilling is currently working his way back from ankle surgery at Triple-A Pawtucket, but Red Sox manager Terry Francona has said that the righthander may pitch out of the bullpen if he is healthy enough to rejoin the major league squad after the All-Star break. Schilling started the season on the disabled list after undergoing surgery on his right ankle during the offseason. He made his first start of 2005 on April 13 against the New York Yankees, then took the mound twice more before going back on the disabled list in late April. Last year Schilling led the majors with 21 wins, ranked second among American League hurlers with a 3.26 ERA and had 203 strikeouts, good for third-best in the AL.