Polanco isn't in the lineup for Tuesday's game against the Cardinals.

Manager Carlos Mendoza said Monday that Polanco has been dealing with a sore Achilles, and the 32-year-old infielder will now get a chance to rest after opening the series with a 2-for-5 performance. Jared Young will pick up a start at first base as a result and bat fifth.

Vaughn underwent successful left hamate bone surgery Monday, Adam McCalvy of MLB.com reports.

Vaughn suffered the injury Opening Day and landed on the 10-day injured list Saturday after tests revealed a fracture. The Brewers hope he will be ready to return around mid-May. Jake Bauers and Gary Sanchez will handle first base for the Brewers while Vaughn is sidelined.

Steer is not in the lineup for Tuesday's game against the Pirates.

Steer is just 1-for-13 at the plate to start the season, so he'll get a day to regroup. Will Benson is handling left field and batting sixth in Steer's stead.

Santana started at first base and went 0-for-3 with a walk in Monday's 9-6 win over the Tigers.

Santana was in the lineup against a right-hander after Pavin Smith (elbow) was placed on the 10-day injured list Monday. The switch-hitting Santana, in theory, could start against pitchers of either hand, but it's uncertain how manager Torey Lovullo wants to handle first base going forward without Smith. Tim Tawa and Ildemaro Vargas are also options. Santana is 1-for-12 through four games played in the regular season.

Mets manager Carlos Mendoza said Monday that Polanco is dealing with a sore Achilles but feels well enough to serve as a designated hitter, Anthony DiComo of MLB.com reports.

Polanco is in the Mets' lineup at DH on Monday in St. Louis and could remain in that slot for a bit as a precaution. Jared Young is getting a start at first base Monday in Polanco's place, but it should be Brett Baty getting the bulk of the reps there until Polanco is able to play the field. Baty is starting in right field Monday.

Stewart went 2-for-2 with a walk, a double and a run scored in Sunday's 3-2 win over the Red Sox.

There was no let-up for Stewart in the third game of the season. He's now had multiple hits and reached base at least three times in all three games, going 7-for-10 with three walks, zero strikeouts and more extra-base hits than singles. He also showed advanced baserunning Sunday, advancing to second base on a flyout to center field, which put him in a position to reach third base when the next batter singled to left field.

Steer started at first base and went 1-for-4 in Sunday's 3-2 win over Boston.

Steer made his first start of the season at first base after serving as the left fielder Thursday and Saturday. The plan announced this spring, when Steer started at five different positions, was that he would primarily play left field but could also slot in at various spots. In addition to his starting positions thus far, Steer also moved mid-game Saturday to first base and then third base. That roster flexibility helps manager Terry Francona navigate in-game situations, while also ensuring Steer gets a full game of plate appearances.

Horwitz will start at first base and bat sixth in Sunday's game against the Mets.

Heading into spring training, the 28-year-old's role was somewhat muddled following the offseason additions of Marcell Ozuna, Ryan O'Hearn and Brandon Lowe, but Horwitz looks to have settled into a strong-side platoon role at first base. He's occupied the position for the Pirates' first two games against right-handed pitchers, with O'Hearn spelling him Saturday when the Mets sent lefty David Peterson to the hill.

Smith went 1-for-4 with a grand slam in Saturday's 6-2 win over the Royals.

Smith played the role of hero Saturday, crushing a walk-off grand slam in his team debut to punctuate Atlanta's six-run comeback in the ninth inning. With Sean Murphy (hip) on the injured list to begin the year and Jurickson Profar suspended for the entire season, the left-handed-hitting Smith has a clear pathway to at-bats at designated hitter versus right-handed pitching for the time being.

Stewart went 2-for-4 with a solo home run, two RBI and a walk in Saturday's 6-5 win over the Red Sox.

Stewart's wrist soreness, which stems from being hit by a 110-mph liner Opening Day, didn't seem to be an issue Saturday, as he stayed hot at the plate. The first baseman had an RBI single in the first inning and then took Sonny Gray deep in the third. Batting cleanup for Cincinnati, Stewart is 5-for-8 with two doubles, one home run and two RBI through two games to begin the regular season.