Boston increased its lead in the AL East to six games over the New York Yankees, who lost to Tampa Bay.
The 23-year-old center fielder played maintenance man in the sixth inning, hanging a number back up on the mechanical scoreboard in left after another rookie, Baltimore left fielder Brandon Moss, knocked it off when he smacked into the wall making a catch in the gap on a drive by Nick Markakis.
"If they make me do it again. I can do it," Ellsbury said. "I just checked my phone. My buddies were laughing at that more than anything."
Ellsbury and Buchholz were called up from Triple-A Pawtucket on Saturday when teams could expand their rosters. Rookie Dustin Pedroia has been the regular second baseman all season and made another diving stop behind second base and threw out a runner -- just like he did to preserve Buchholz's no-hitter in the seventh.
Two pitchers who were rookies last season, Jon Lester (3-0) and Jonathan Papelbon, who got his 31st save in 33 chances, held the Orioles in check. Lester pitched six strong innings and Papelbon retired the side in order in the ninth.
"We talk for a few years now how our biggest organizational challenge is to develop players who can come up and contribute during a pennant race," general manager Theo Epstein said. "We saw a little bit of that this weekend."
Pedroia went 2-for-4 and was 8-for-14 in the series. He is batting .347 in his last 40 games after getting off to a slow start at the plate.
"We've got a lot of talented young players," Pedroia said. "I came up here, took my lumps, but the organization has confidence in the young players."
"When you get scoring opportunities against this club, you better take advantage of them," Orioles manager Dave Trembley said, "and we didn't."
The Orioles lost their second straight game after breaking a nine-game losing streak with a 9-8 win Friday night.
They lost 10-0 Saturday and had gone 12 1/3 innings without a hit before Huff singled with one out in the second off Lester. Their next hit came in the fourth, a single by Huff that loaded the bases. Melvin Mora lined out to Pedroia and Ramon Hernandez hit into a double play when right fielder J.D. Drew caught his short fly and threw out Tejada trying to score.
"Nothing's working for us now," Huff said. "If there are baseball gods, they're certainly frowning on us."
They made it 2-0 in the fourth on Ellsbury's first career homer. He had 19 at-bats in two previous stints with Boston this year.
"That gets a lot of firsts out of the way," he said. "After that's over, you just go out and play."
Boston added a run in the fifth on a double by Pedroia, who took third on Alex Cora's sacrifice and scored on Lowell's sacrifice fly.
"I love it," Lowell said of the rookies' contributions. "There is absolutely a hunger and they're also very athletic guys."
Lester ran into trouble in the sixth. With one out, singles by Tejada and Millar put runners at first and second. Mora drove in Tejada with a single to left.
Hernandez led off the seventh with his third homer of the season, knocking Lester out of the game after throwing 90 pitches. Javier Lopez came in and retired the next three batters.
Okajima allowed a leadoff double in the eighth to Nick Markakis, who took third on Tejada's groundout to Pedroia. Then the lefty got out of the jam with the strikeouts.
- Lowell extended his hitting streak to 15 games.
- In his last 11 appearances, Papelbon has eight saves in 10 2/3 scoreless innings with 18 strikeouts while allowing one hit.
- Baltimore's ERA is 9.16 in its current 1-11 slide.
- Cabrera has allowed five homers in his last five starts.