A number of successful southpaws take the mound as part of a full 15-game slate today, while the Yankees and Red Sox match up for the first time this season in a game featuring a pair of right-handers, streaming live on MLB.TV.
The Cubs' Jonathan Lester takes on the Pirates for the second time this year, while lefties go head-to-head when the Mariners meet the Tigers and the Twins face the Rangers.
Seattle's James Paxton gets the ball opposite Detroit's Daniel Norris, and Minnesota's Hector Santiago is set to oppose Texas' Cole Hamels.

After Tuesday's scheduled series opener was postponed due to rainy weather in Boston, the Red Sox will send reigning American League Cy Young Award winner Rick Porcello to the mound tonight at Fenway Park opposite the Yankees' Luis Severino.
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Here's what else to watch for throughout the day (all times in ET):
Lester looking to rebound: CHC@PIT, 7:05 p.m.
Lester is back in his usual spot in Chicago's rotation after manager Joe Maddon made some tweaks to his staff that will allow Lester to face Pittsburgh tonight instead of Boston later in the week.
Maddon is taking advantage of his club's off-days to play the matchups in favor of his pitchers. The Pirates have struggled against left-handed pitching so far in 2017, though Lester is coming off a tough outing in which he allowed five runs in 5 2/3 innings at Cincinnati last Friday.
"We wanted to get it back to where it had been, and we like the way it sets up," Maddon said of the rotation switch.
Perhaps an appointment with the Pirates is the remedy for Lester, who threw seven scoreless innings against the Bucs on April 16. The Cubs' Opening Day starter will face young righty Tyler Glasnow, who is 0-1 with a 7.94 ERA in three starts this season.

Showdown in Motown: SEA@DET, 7:10 p.m.
Paxton and Norris will each attempt to bounce back after rocky showings in their previous outings after a strong start to the year.
Paxton's 23-inning scoreless streak to begin the season came to an end against the A's, who got to the 28-year-old for five runs in 4 1/3 frames in what was his first subpar performance of the year.

Norris also started 2017 on a high note with consecutive games of at least six innings, but he struggled against Tampa Bay when he gave up five runs (four earned) in 4 2/3 frames in his first loss.
Both lefties try to right the ship when they battle one another at Comerica Park in Detroit.

Rivalry renewed: NYY@BOS, 7:10 p.m.
The Red Sox should have Dustin Pedroia back in the lineup, as the rainout gave him an extra day to recover after injuring his left knee and ankle in the series against the O's.
The Yanks, who are off to a better start than many expected, will hope for some more big hits out of their young slugger Aaron Judge, who's getting his first taste of the rivalry.

Southpaws square off: MIN@TEX, 8:05 p.m.
Santiago seems to be enjoying his first full season with Minnesota. A 2016 non-waiver Trade Deadline deal sent him from the Angels to the Twins, and after going 3-6 with a 5.58 ERA for his new club last year, he's 2-1 with a 2.19 ERA through four starts in 2017.

The 29-year-old has averaged just over six innings per start and has struck out six batters in each of his last two times on the mound. His date with the Rangers will mark Santiago's first of the year that will not be against an American League Central opponent.
Hamels gets the ball on the heels of his longest start of the season, an eight-inning gem in which he allowed just one run against Kansas City. The 33-year-old has put up strong numbers so far this year (1-0, 2.77 ERA), but he is lacking in the strikeout department (14 K's over 26 IP).