The Red Sox recalled promising shortstop Jose Iglesias, outfielder Che-Hsuan Lin and right-hander Junichi Tazawa from Triple-A Pawtucket before Saturday's game against the Royals.
Iglesias was hitting .329 in 19 games for Pawtucket this month. He had a brief stint with the Red Sox in early May, but did appear in a game, though he played in 10 games for Boston in 2011. Iglesias is rated as Boston's No. 11 overall prospect by MLB.com.
"He's here kind of because we needed an extra infielder for [Saturday]," Valentine said. "I don't have that plan [going forward] yet."
Pedro Ciriaco, who started at third on Saturday, will continue to play multiple positions in the infield.
Lin hit .247 with two homers and 30 RBIs in 107 games for Pawtucket. He joins the Red Sox for the third time this season. Lin has appeared in six games with Boston, starting once.
Tazawa is also on his third stint with the Sox. He has a 1.37 ERA and one save in 20 appearances with Boston this year.
The Red Sox also acquired first baseman James Loney from the Dodgers. He was not with the team on Saturday but is expected to be in uniform for Sunday's game against the Royals.
"He's a good defender, he's very durable, he's played a lot," Red Sox general manager Ben Cherington said. "We think he's got a pretty good swing for Fenway. I think he's excited to hit in a different ballpark."
Mauro Gomez started at first base for the second straight game on Saturday. He made the most of his opportunity -- belting his first career homer over the Green Monster in his first at-bat.
Gomez and Loney are expected to both spend time at first base.
"Not a real strong plan yet," Valentine said. "If we have James here in uniform, he'll definitely be part of that plan."