Harper hit the two home runs in a Monday game against the Miami Marlins. 

Sen. Mark WarnerMark Robert WarnerBipartisan group of lawmakers aim to reform US sugar program The Hill interview — DNC chief: I came here to win elections Virginia's governor race: What to watch for MORE (D-Va.) was in the ballpark in Washington during the game.

And Senate Majority Leader Harry ReidHarry ReidTop Lobbyists 2017: Grass roots Boehner confronted Reid after criticism from Senate floor GOP in uncharted territory rolling back rules through resolutions MORE (D-Nev.) tweeted later on in the game that he hoped 2013 would be an "MVP season" for Harper. Harper, who is 20 years old, won the 2012 National League Rookie of the Year award.

Elsewhere on opening day, Sen. Chris MurphyChristopher (Chris) Scott MurphyDems mull big changes after Brazile bombshell After Texas shooting, lawmakers question whether military has systemic reporting problem Warren to GOP: Thoughts and prayers not enough after Texas shooting MORE (D-Conn.) struck what could be a pessimistic note for Red Sox fans.

The Red Sox faced off against the New York Yankees.