WEST PALM BEACH, Fla. -- There were runners at first and second for the Red Sox with one out in the fourth, and catcher Blake Swihart hit a grounder back to the mound. The Nationals were thinking -- or at least hoping -- for an inning-ending double play.Jackie Bradley Jr.

WEST PALM BEACH, Fla. -- There were runners at first and second for the Red Sox with one out in the fourth, and catcher Blake Swihart hit a grounder back to the mound. The Nationals were thinking -- or at least hoping -- for an inning-ending double play.

Jackie Bradley Jr. was contemplating something much bolder. As right-hander Vance Worley threw to second, Bradley raced toward third ... and never stopped.

Nats first baseman Ryan Zimmerman threw to the plate as soon as he received the tardy double-play attempt by shortstop Trea Turner , but Bradley slid in head-first under the tag of catcher Derek Norris . The play was a clear highlight for the Red Sox in a 5-3 win over the Nationals.

"That's huge. I practice it," Bradley said. "It's something that I'll continue to do to push the envelope and extend leads."

It is the type of aggression the Red Sox preach.

"Absolutely," said Bradley. "There's really no such thing as making an aggressive mistake right now. Every single thing that we're doing is for a purpose. We'll see the means of it at the end of the road."

As Bradley ran back in, Boston's dugout erupted with the type of emotion you don't see often during Spring Training.

"Just a great heads-up play," said Red Sox manager John Farrell. "He obviously anticipated it knowing the throwing capability of Zimmerman and possibly taking advantage of it. He never broke stride. It's an exciting play. You're scoring from second base on a ball in the infield. It gives you a quick jolt of energy, regardless of the time of the season."