BOSTON -- Center fielder Mookie Betts' first two innings of Boston's home opener Monday afternoon included a home-run-robbing catch, two stolen bases on one play and a three-run homer -- a scintillating start that sparked the Red Sox to a 9-4 win over the Washington Nationals.

Rick Porcello allowed four runs (three earned) over eight innings, designated hitter David Ortiz hit his second homer of the season and catcher Sandy Leon recorded his first three hits as a member of the Red Sox, who improved to 5-2.

First baseman Ryan Zimmerman hit his second home run and center fielder Danny Espinosa added his first for the Nationals (2-5), who have lost four of the past five.

But Boston's leadoff hitter stole the show.

The 22-year-old phenom made his major-league debut midway through last season and batted .291 with five homers and 18 RBIs in 52 games.

If Monday was any indication of what's ahead, it could be a memorable MVP-type of year.

Betts robbed right fielder Bryce Harper of a two-run homer in the top of the first inning, leaping above the short wall in front of Boston's bullpen to make the catch.

He then put his electric base-running skills on display in the bottom half. With the infield shift employed against Ortiz, the speedster stole second, sliding headfirst, promptly rose to his feet and dived headfirst into third just ahead of the tag by Washington starter Jordan Zimmermann.

Nationals manager Matt Williams unsuccessfully challenged the rulings at both second and third.

Ortiz then slapped Zimmermann's next pitch over the head of left fielder Jayson Werth for a 1-0 lead.

Betts made it 4-0 an inning later with his second homer of the season, belting a 1-1 slider from Zimmermann into the seats above the Green Monster.

Boston tacked on four more in the third on two hit batsmen, a pair of fly balls that dropped in the sun, an RBI single by Betts and a sacrifice fly from second baseman Dustin Pedroia.

That was more than enough support for Porcello, who earned his first win with Boston since being acquired in the offseason and signing a four-year, $82.5 million contract extension last week.

Porcello (1-1) allowed four hits and one walk, with six strikeouts. He retired 11 of the first 13 batters before Zimmerman's blast leading off the fifth.

Zimmermann (1-1) lasted just 2 1/3 innings. The right-hander allowed eight runs (seven earned) on nine hits and one walk.

NOTES: New England Patriots QB Tom Brady threw the ceremonial first pitch after joining coach Bill Belichick and owners Robert and Jonathan Kraft in carrying the franchise's four Super Bowl trophies onto the field. ... Boston improved to 69-46 in home openers. ... The Red Sox activated closer Koji Uehara from the 15-day DL and optioned LHP Tommy Layne to Triple-A Pawtucket. ... LF Jayson Werth started for Washington after being activated from the 15-day DL, where he started the season after shoulder surgery. Matt den Dekker was optioned to Triple-A Syracuse.