What's Next: Giants-Dodgers, Yanks-Red Sox rivalries heat up

A-Rod may tie Mays with No. 660; top White Sox prospect Rodon could get first start

What's Next: Giants-Dodgers, Yanks-Red Sox rivalries heat up

The calendar will change from April to May later this week, and the long season keeps steaming forward.

Friday brings May Day, Saturday brings the Kentucky Derby, and the second month of the six-month horse race called Major League Baseball continues on the bumpy road to October. But starting Monday, the week ahead is jam-packed with sizzling storylines.

There's likely going to be the confirmation of a crushing injury that will alter a team's plan moving forward. There will be the aftermath of last week's suspensions. And there will be intense matchups galore played out on the diamonds of the American League and the National League.

The Royals and White Sox are going to have to deal with their new reality after their well-publicized donnybrook Thursday night at U.S. Cellular Field. The White Sox will head to Baltimore for a week-opening set against the Orioles, and while they appeal the suspensions of Nos. 1 and 2 starters Jeff Samardzija and Chris Sale, they'll have to fill in the roster cracks if necessary.

White Sox on Royals' altercation

That could very well mean fans on the South Side will soon see the Major League starting debut of the team's No. 1 pick in the First-Year Player Draft last year, lefty Carlos Rodon.

The Royals will have to gear up for a weekender against the team they're chasing in the AL Central, the Detroit Tigers, while wondering what the immediate future might hold for suspended starters Yordano Ventura and Edinson Volquez, outfielder Lorenzo Cain and reliever Kelvin Herrera.

Those aren't the only rivalries on tap this week, though.

The Giants will meet their archrival Dodgers. The Yankees will meet their archrival Red Sox, and Alex Rodriguez might hit career home run No. 660 and meet Willie Mays in the record books.

And the surprising NL East-leading Mets will be up against the Nationals, who were favored to win the division but have gotten off to a bit of a slow start.

In other words, the first-month jitters are over. The sample sizes just aren't that small anymore. It's the last week of April, and baseball is about to get even better.

Waino watch

In St. Louis, the mood is a bit more somber than excited, as ace and team leader Adam Wainwright will undergo an MRI exam Monday to determine the severity of what the club is calling an injury to his left Achilles tendon and left ankle. If it's a rupture, Wainwright will be out for the season and the Cardinals would have to figure out what to do next.

And judging by the mood of the team Sunday, the day after Wainwright suffered the injury while breaking out of the batter's box on a fifth-inning popup, it sure seems like something significant.

"It's pretty somber right now, just because I don't know of a more respected guy on the team, but also this stuff happens," Cards manager Mike Matheny said.

Mozeliak on Wainwright injury

"You lose guys. We went into this [season] realizing that there's a high probability that we'd have somebody go down at some point and have to have somebody step up. That's part of why we need some depth in the organization and have other guys ready to go. But right now, we're not going to get too far ahead until we see things for sure on Monday. But [it's] definitely not a good thing."

Losing Wainwright for the remainder of 2015 would be a terrible break for the Cardinals, who have gotten off to a great start and are being chased by the Pirates and Cubs in the NL Central.

Both of those clubs are also hot to begin the year, and they play each other this week at Wrigley Field, with Vance Worley toeing the slab for Pittsburgh and Jason Hammel pitching for Chicago in the three-game series opener Monday night.

Doug Miller is a reporter for MLB.com. Follow him on Twitter @DougMillerMLB. This story was not subject to the approval of Major League Baseball or its clubs.