BOSTON (AP) — Fans stood and cheered John Lackey only five days after another Fenway Park crowd booed Boston’s struggling starter following his worst performance in a Red Sox uniform.

“It was nice,” he said with little emotion.

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Boston's John Lackey pitched 6 2/3 shut out innings as the Red Sox beat the Orioles 4-0 on Saturday. AP

The 10-year veteran struggling through his second season with Boston took the cheers in stride, just as he did his best outing of the year — a 4-0 win over the Baltimore Orioles in which he allowed three hits in 6 2-3 innings on Saturday night.

“There’s a fine line between good and bad,” Lackey said. “My arm felt about the same as it did in the last start, honestly.”

It followed a stint of 2 1-3 innings in which he allowed seven runs in a 9-7 loss to the Toronto Blue Jays. His velocity was about the same, but his improved location gave the Orioles trouble.

Red Sox manager Terry Francona was pleased with the fans’ change of heart toward Lackey.

“Our fans are dying to show their appreciation,” he said. “I know they boo sometimes. They care about their team.”

Lackey lowered his ERA from 7.47 to 6.84 and ended his three-game losing streak. The Red Sox won their fifth straight game and ninth in their past 10.

“He has a pedigree of pitching pretty well,” Baltimore manager Buck Showalter said. “He hasn’t done it much, but he did tonight.”

Alfredo Simon (1-2) allowed three runs in the fifth on an RBI double by Kevin Youkilis and a two-run double by Josh Reddick.

Youkilis added another run-scoring double in the seventh off Mark Hendrickson.

Boston maintained its one-game lead in the AL East over the New York Yankees, who beat the Tampa Bay Rays 5-4.

The Orioles, last in the division, suffered their sixth straight loss and 11th in 12 games.

“I was just trying to keep the game close,” Simon said. “I think I did a good job with all of my pitches. I’m happy with the way I pitched.”

Lackey got a standing ovation as he strode to the dugout when he was replaced by Daniel Bard with two outs and runners at first and second in the seventh. They were stranded when Nolan Reimold popped out to shortstop Marco Scutaro.

Bard then struck out two in the eighth, extending his streak to 18 1-3 scoreless innings. But he was left off the AL team for Tuesday’s All-Star game.

“If Daniel Bard’s not (an All-Star) nobody is,” Francona said. “I know the rules are what they are, but he’s some kind of good.”

Lackey struck out seven and walked one the day after Boston’s 10-3 win in which the benches cleared twice in the eighth inning, the first after Kevin Gregg’s inside pitch to David Ortiz and the second after Ortiz charged Gregg when the pitcher gestured at him as he started down the first-base line on a fly out.

Both punched at each other, but failed to connect

Ortiz apologized on Saturday “to everyone for the situation. … Even to Gregg.”

Lackey hit two batters on Saturday. Nick Markakis went directly to first after being hit in the sixth. With two outs and no runners on in the seventh, Lackey hit Derek Lee below his left hip. Plate umpire Jeff Nelson warned both benches.

The Red Sox didn’t need Ortiz’s actions Friday to spur them on, Lackey said, but “it might have made us a little closer.”

Simon, a former closer making his first start since April 14, 2009, fell behind 3-0 in the fifth after retiring the first batter.

“He just couldn’t hold that offense off forever,” Showalter said.

Jacoby Ellsbury then tripled but was out at home on a hard grounder to Simon by Dustin Pedroia, who took second. After an intentional walk to Adrian Gonzalez, Youkilis doubled in the first run. Ortiz also was walked intentionally, a move that backfired when Reddick hit his two-run double.

In the seventh, Pedroia stretched his hitting streak to 11 games with a leadoff double and scored on Youkilis’ double.

The Orioles managed just four singles — three against Lackey, one off Bard and none off Jonathan Papelbon, who worked the ninth.

NOTES: The Red Sox hit no homers after getting eight in the first two games of the series. … Simon is the 24th Baltimore starter in the last 25 games to last fewer than seven innings. … In Sunday’s finale of the four-game series, RHP Kyle Weiland is scheduled to make his major-league debut for Boston, while Baltimore RHP Mitch Atkins makes his second major-league start. … The Orioles called up LHP Hendrickson from Triple-A Norfolk and sent LHP Zach Britton to Double-A. Britton allowed eight runs in the first inning of Boston’s win on Friday night, becoming the third Orioles pitcher since they moved to Baltimore in 1954 to give up at least eight runs without making it out of the first. The others were Hayden Penn on Sept. 3, 2006, and Victor Zambrano on Sept. 26, 2007.