PORT ST. LUCIE, Fla. -- Stephen Strasburg had a rocky return to the mound in his first outing since the Washington Nationals shut him down last September to protect his arm.

Strasburg gave up a single and a full-count homer to the first two batters he faced Saturday, and the New York Mets beat Washington 5-3 in a spring training opener.

Kirk Nieuwenhuis led off the Mets' first inning with a single and Ruben Tejada followed with a two-run shot that the wind carried over the left-center fence.

"It was a little bit of a debacle the first inning, but that's just what happens for me every spring training," Strasburg said. "It's just going to take a little while for me to get a little comfortable, a better rhythm out there. I was just glad I was able to get back feeling right in the second inning."

The right-hander rebounded with a 1-2-3 second inning. He was pitching in a game for the first time since Sept. 7 when the NL East champions shut him down for the season, rather than push his innings total.

Mets newcomer Shaun Marcum gave up four hits and three runs in two innings. Top prospect Zack Wheeler pitched two shutout innings.

Strasburg also gave up a two-out double to Marlon Byrd in the first but ended a 29-pitch inning by striking out Lucas Duda.

Strasburg allowed three hits in two innings. He struck out two, walked none and threw 24-of-42 pitches for strikes.

"I threw a couple good breaking balls in the second inning, and my fastball command got better and the sinker seemed to be working well," Strasburg said. "It was a good first outing."

Strasburg also gave up a home run in his 2012 spring training debut, to Chris Snyder, his batterymate Saturday.

"He settled down a little the second inning, dropped his pitches in, was effective and we'll go from there," Snyder said. "He's got good stuff. It's hard. The two-seamer has good stuff to it, and the curveball and changeup are both putaway pitches."

The Mets are similarly excited about Wheeler, who was impressive in relief of Marcum.

After Marcum gave up a two-run homer to Snyder in the second, Wheeler allowed just one hit and one walk while throwing 19 of 30 pitches for strikes.

"He's got a great arm," Mets manager Terry Collins said. "I was impressed with his breaking ball. I'm sure he was a little geeked up going out there. The second inning he pounded the strike zone. That was great to see."

Wheeler had to work himself out of an early jam, though. After walking his first batter, he threw a wild pitch to Bryce Harper but got him on a groundout and then struck out the next two batters to strand a runner on third.

"It wasn't really nerves. I just was a little pumped up getting out there," said Wheeler, expected to begin the season at Triple-A Las Vegas. "After the first couple batters, I think everything went well. I was getting underneath my slider a little bit. It was backing up, but I still got some swings and misses from it."

Game notes

With the score tied at 3, Collin Cowgill hit an RBI double in the sixth inning to drive in the go-ahead run for the Mets. Bobby Parnell closed the game with a shutout inning. ... Mets reliever Pedro Feliciano has been diagnosed with a small hole in the exterior of his heart, but upon returning to camp Saturday morning, he said it is not life-threatening. The left-hander underwent an MRI in New York, where he was sent after an irregular heartbeat was discovered in his pre-camp physical. Feliciano will wear a heart monitor for a few days and has not been cleared to pitch. ... Nationals pitcher Christian Garcia received a second opinion on his strained forearm, but the diagnosis remained the same. Manager Davey Johnson said he still doesn't believe the injury is severe.