Keller, the Pirates' top pitching prospect, has gone 5-0 with a 3.45 ERA over nine starts for Triple-A Indianapolis this season and was scheduled to start for that club in Columbus, Ohio, on Sunday. Keller, 23, will start the second game in Cincinnati, the Pirates announced in a tweet on Sunday.
A second-round pick by the Pirates in 2014, Keller has a 34-17 record with a 3.06 ERA over six minor league seasons. Injuries to starters Trevor Williams, Jameson Taillon and Chris Archer have left the Pirates hurting for pitching -- though Archer returned to the rotation on May 15.
When Keller does take the mound, he won't be throwing to Francisco Cervelli. The Pirates placed their starting catcher on the 7-day concussion list after he took a broken bat to the facemask during Saturday's game against the Los Angeles Dodgers.
This is the third straight season in which Cervelli has suffered a concussion, and he has a long history of dealing with them.
Cervelli, 33, is batting .193 with a homer and five RBIs in 34 games this season. Elias Diaz (.250 entering Sunday) will be the primary catcher during Cervelli's absence. Pittsburgh also recalled catcher Jacob Stallings and infielder-outfielder Jose Osuna from Triple-A Indianapolis, while designating utility man Jake Elmore for assignment.
--After leaving Saturday's start after just three batters, Boston Red Sox hurler David Price is expected to be moved up in the rotation for his next start, perhaps Tuesday or Wednesday against the Cleveland Indians at Fenway Park, according to Ian Browne of MLB.com.
With Price's absence taxing the bullpen on Saturday, the Red Sox called up fellow left-hander Darwinzon Hernandez from Double-A Portland and sent right-hander Colten Brewer down to Triple-A.
Price, 33, is 2-2 in eight starts this season, sporting a 3.24 ERA and 1.08 WHIP.
Left-hander Robbie Erlin started as the opener for San Diego and took the loss, giving up one run in two innings as the Padres lost 10-1.
Paddack, a 23-year-old rookie off to a 4-2 start with a 1.93 ERA in nine starts. He is scheduled to make his next start on Wednesday against the host New York Yankees.
--The New York Mets activated outfielder Michael Conforto from the 7-day concussion list prior to their game against the Detroit Tigers.
Conforto started in right, batted third and went 0-for-3 in New York's 4-3 win. Conforto, 26, suffered the concussion during a game against the Washington Nationals on May 16. He is batting .265 with nine homers and 21 RBIs in 43 games this season.
The Mets designated outfielder Rajai Davis for assignment to make room for Conforto, though the team hopes it can hold onto Davis.
--Both Los Angeles teams activated their Sunday starting pitchers from the injured list prior to their respective games, as the Angels activated left-hander Andrew Heaney for his season debut against Texas and the Dodgers activated right-hander Kenta Maeda before their series finale in Pittsburgh.
Heaney had been sidelined since experiencing elbow inflammation during spring training. He gave up two runs on two hits -- both solo home runs -- with eight strikeouts and a walk. He did not get a decision as the Angels beat Texas 7-6 in Anaheim, Calif.
Maeda had been sidelined by a left adductor contusion since May 16. He improved to 6-2 on the season after going five innings and giving up three runs on five hits with no walks and four strikeouts. The Dodgers beat the Pirates 11-7 to sweep the three-game series.
--Field Level Media