The Boston Red Sox got a boost to their bullpen before opening a three-game road series against the Seattle Mariners Monday night.The Red Sox reinstated relief pitcher Hirokazu Sawamura from the COVID-19-related injured list. The 33-year-old right-hander spent nearly two weeks on the COVID IL after he tested positive for the coronavirus on Aug. 31.Sawamura is in his first season with the Red Sox after signing as a free agent on Feb. 16. He played in Japan's Nippon Professional Baseball league for 10 seasons before joining Boston.The reliever has appeared in 50 games for the Sox this season with a win-loss record of 4-1, a 3.09 earned run average and 54 strikeouts in 46 2/3 innings.On Sunday, the Red Sox reinstated starting pitcher Nick Pivetta from the COVID-19 IL but placed reliever Phillips Valdez on the list after he tested positive for the coronavirus.Boston now has nine players on its COVID-19 injured list: starting pitcher Chris Sale, All-Star closer Matt Barnes, rookie outfielder Jarren Duran, infielder Christian Arroyo, left-handed pitcher Martín Pérez, infielder Jonathan Araúz, infielder Yairo Muñoz, utility player Danny Santana and Valdez.Santana was placed back on the COVID-19 IL on Saturday, just four days after he was reinstated from the list.After Saturday's game against the Chicago White Sox, Red Sox manager Alex Cora said Barnes and Pérez are headed to Worcester for rehab assignments. Cora said Barnes will likely need two rehab outings, with Pérez making one or two.In addition to reinstating Sawamura, the Sox activated left-handed pitcher Austin Davis from the paternity leave list on Monday.Davis has made 14 appearances for Boston since he was acquired in a trade with the Pittsburgh Pirates on July 30. The 28-year-old has posted a 4.61 ERA with 14 strikeouts and six walks in 13 2/3 innings pitches. Eight of his last nine outings have been scoreless, including both of his appearances in September.To make room for Davis and Sawamura on the active roster, the Red Sox sent left-handed pitcher Stephen Gonsalves and right-handed pitcher Brad Peacock down to Triple-A Worcester.Gonsalves made three relief appearances for Boston after being promoted to the major leagues on Aug. 31, allowing two runs in 4 1/3 innings. The 27-year-old has a 4-4 record with a 4.97 ERA in 17 appearances, including 10 starts, with Worcester this year.Peacock, a member of the Houston Astros' 2017 title-winning team, was acquired by the Red Sox in an Aug. 30 trade with the Cleveland Indians. He made two appearances with Boston, including one start, and has an 0-1 record and 15.19 ERA after allowing nine earned runs in 5 1/3 innings pitched.Finally, the Red Sox reinstated right-handed pitcher Eduardo Bazardo from the 60-day injured list and optioned him to Triple-A Worcester.Bazardo made two relief appearances with Boston, April 14 and May 12, which were the first outings of his major league career. He did not allow a run in three innings pitched.The 26-year-old was placed on the minor league injured list on May 22 and then transferred to the major league 60-day IL on July 5 with a right lat strain. He made three rehab appearances in the Florida Complex League and four with Worcester.