Pettitte had little trouble against a tough Washington lineup. The 40-year-old left-hander breezed through six innings, allowing two runs (one earned) on five hits.
Pettitte struck out six without issuing a walk, and his biggest problem came when Wilson Ramos' bat came flying near his head in the third -- but Pettitte got out of the way.
"I feel great," said Pettitte. "I'm a little concerned with just being too strong, so I just wanted to make sure I got good work in today. I think they were good after five. I get a little amped up if I don't feel like I'm getting my work in. Hopefully, I got ... enough work in."
The 34-year-old Youkilis has gotten in plenty of good work throughout the spring. He lined a 1-2 pitch off Jordan Zimmermann into the New York bullpen to open a four-run fourth inning. That frame gave the Yankees all the offense they needed.
Youkilis has been swinging a powerful bat all spring. Because Friday's homer came in an exhibition game, it didn't count toward his Grapefruit League statistics, but in Grapefruit League play, the veteran recorded 13 hits, 12 of which went for extra bases.
"Spring is spring," Youkilis said. "You've got to keep with your strengths, and there are times when you find things you're doing wrong and you've got to learn from them. I had those days. It's about doing that all year and just trying to make adjustments. That's my whole goal this year -- make quick adjustments."
The 43-year-old Rivera, who recently announced that this season will be his last, came on in the ninth and needed just 10 pitches to retire the side in order.
The Yankees' big fourth inning proved to be enough. After the Youkilis homer, Eduardo Nunez added a two-run single to make it 3-0. Nunez scored on a gamble, racing home from third while the Nationals were trying to throw out Chris Stewart as the backup catcher rounded first base too far after singling.
Ryan Zimmerman scored both of Washington's runs. In the fourth, Zimmerman crossed the plate after reaching second on Youkilis' throwing error from third base. Ian Desmond drove in Zimmerman with a single.
Zimmerman added a two-out double in the sixth, and Adam LaRoche followed with an RBI single to cut New York's lead to 4-2.
Zimmermann lasted 3 1/3 innings for the Nationals, giving up four runs on seven hits. Right-handed reliever Henry Rodriguez, who learned after the game that he had edged lefty J.C. Romero for the final spot on Washington's roster, worked a scoreless sixth inning.
Washington's bullpen threw well, holding New York scoreless on three hits in 5 2/3 innings. Zach Duke, Rodriguez, Ryan Mattheus, Tyler Clippard and Drew Storen combined to strike out seven and walk just one.
"It was a good day for the bullpen," Nationals manager Davey Johnson said. "I liked what I saw today, because that was a good day for five of my bullpen guys to get work and follow each other. That was kind of the pecking order."
Up next: Spring competition has wrapped up for the Nationals, whose next game will be Monday's regular-season opener against the Marlins. Stephen Strasburg will take the hill at Nationals Park opposite Miami's Ricky Nolasco in the 1:05 p.m. ET start.