The Mariners will play their first doubleheader of 2021 on Tuesday after rain in Baltimore postponed their four-game series opener on Monday. Seattle will stay on line with its pitching plans, with Justus Sheffield slated to start the matinee at 1:05 p.m. PT and Nick Margevicius set for the nightcap 45 minutes following the final out of Game 1 (but no earlier than 4:05 p.m. PT). Sheffield will look to rebound from a tough 2021 debut against the White Sox, when he allowed six runs and struggled with command. Then after, Margevicius will make his first turn through the rotation in place of the injured James Paxton. Margevicius hasn’t pitched since coming in to relieve Paxton when Big Maple exited his 2021 debut in the second inning last Tuesday against Chicago. Fans can catch all the action from Oriole Park at Camden Yards live on MLB.TV.