PORT ST. LUCIE, Fla. — Nervous? Not at all. Bryce Harper said he was perfectly comfortable during his much-anticipated debut with the Washington Nationals — maybe even too comfortable.

PORT ST. LUCIE, Fla. — Nervous? Not at all. Bryce Harper said he was perfectly comfortable during his much-anticipated debut with the Washington Nationals — maybe even too comfortable.

The 18-year-old phenom struck out twice and didn't see any action in the field Monday as the Nationals beat the New York Mets 9-3 in their spring training opener. But the top pick in last year's amateur draft cleared a hurdle with his first two at-bats against big league competition.

"I felt really comfortable out there," Harper said. "I might have felt a little too comfortable, so I'm going to go out there tomorrow and the next day and try to get a few base hits and see what happens.

"It's like I feel way too strong," he added. "I feel way too quick. I feel like I can turn over a 150 mph fastball. I felt really good. I just need to stay back on my back side a little more and try to hit it over the third baseman's head."

Harper entered as a pinch runner for designated hitter Matt Stairs in the fifth inning and finally got a plate appearance in the seventh. Harper fouled off the first pitch from lefty Taylor Tankersley, then swung and missed on the next two.

In the top of the ninth, Harper struck out on four pitches against right-hander Ryota Igarashi.

When Harper went up to the plate for his first at-bat, the Nationals already had a 7-3 lead.

"I wasn't nervous," Harper said. "After seeing everybody go up there swinging, getting their swings in and stuff, that's what I wanted to do. I wanted to go up there and get my hacks in, and that's just me. I don't like taking it, so I'm going to go up there swinging."

Washington manager Jim Riggleman said he had hoped Harper's first at-bat would come against a right-hander, but he was glad the young catcher-turned-outfielder could see both types of pitchers.

"I felt the pitches were really tough," Riggleman said. "I'm sure he was nervous, but he was aggressive. He was really hacking at it."

Harper said he is under the impression he will be in major league camp for only a couple more games, but he thinks any experience getting live at-bats against major league pitching will benefit him as he tries to make his way to the big leagues.

The left-handed hitting slugger is slated to start the season in low Class-A Hagerstown but is looking for a quick rise through the farm system.

He skipped his final year of high school, obtained his GED and played junior college ball at the College of Southern Nevada for one season in order to become eligible for the 2010 draft and jump-start his professional career.

Harper signed a five-year, $9.9 million contract, including $6.5 million in signing bonuses, with the Nationals last August, too late for the regular minor league season. He did play in the Florida Instructional League, hitting .319 with four homers, four doubles, a triple and 12 RBIs before going on to the Arizona Fall League, where he batted .343.

Red Sox

Red Sox right-hander Josh Beckett has mild concussion symptoms, according to the team, after he was hit in the back of the head on Monday during batting practice before Boston's exhibition game against the Minnesota Twins at City of Palms Park.

Beckett walked from the field on his own, with trainers at his side. But after being examined by a doctor, he was sent home to rest. The Red Sox expect an update today.

Beckett was in the outfield when coaching staff assistant Ino Guerrero attempted to use a fungo bat to return a ball to the infield. Instead, the ball hit Beckett.

Beckett is coming off a disappointing, injury-riddled 6-6 season, in which he had a 5.78 ERA. Beckett, a 1999 first-round pick of the Florida Marlins, is 112-74 for his career, with four shutouts and nine complete games. This is his sixth season with the Red Sox.

Beckett started Sunday night against the Twins and lasted two innings. He was scheduled to pitch next on Thursday against the Phillies in Fort Myers. But manager Terry Francona said it was too early to make a decision on that yet.

Yankees

Derek Jeter will be doing extra work with hitting coach Kevin Long as the New York Yankees captain adjusts to a change in his stride at the plate.

The pair are set for an additional session today at the Yankees' complex. Jeter was not scheduled to make the road trip for a spring training game against Pittsburgh.

Jeter is no longer striding with his left foot. He made a smaller adjustment late last season, shortening his stride after a session with Long.

Jeter batted .270 last year, 44 points below his career average. Early on this year, he's acknowledged that he doesn't feel comfortable at the plate, and he asked Long for more help.