BOSTON – With firefighters from Bath serving as the color guard, Michela Boissonneault of Portland sang the national anthem, drawing cheers as she belted out “land of the free “

Maine Day at Fenway Park was off to a good start.

It got better on a sun-splashed Sunday afternoon as the Boston Red Sox continued their resurgence in this opening month of the major league season.

After a 6-1 win over the Houston Astros — a lowly team welcomed with open arms by the rest of the American League — the Red Sox are 18-7, matching their best start since 2002.

And now for some obligatory disclaimers.

It is only 25 games. That 2002 team played 39-43 ball over the summer months — not a collapse, but enough to knock Boston out of the playoffs.

The 2013 start includes a 9-1 record against last-place teams, including the just-completed four-game sweep over Houston.

So it’s early and the Red Sox are beating up on lowly teams. Everybody got that? Good.

Now here are two reasons why you can still feel giddy about this Boston team: starting pitching and roster depth.

Starting pitching. The top of the rotation is lights out, and the bottom is filling in nicely.

Jon Lester (4-0, 2.27 ERA) looks like an ace, and he has been the second-best pitcher in Boston, with Clay Buchholz 5-0 (1.19).

Then there is Ryan Dempster (3.30 ERA), Felix Doubront (3-0) and the repaired-and-improved John Lackey (2.61 ERA).

Yes, facing Houston may be only a slight step above rehabbing in Triple-A, but Lackey looked sharp enough Sunday, retiring 13 straight batters at one point. He had a rough first inning (one run, two walks, 27 pitches) and pitched out of a bases-loaded, one-out jam in the sixth.

“He gave us more than we anticipated.,” Red Sox Manager John Farrell said. “The way he continued to pound the strike zone from the second to the sixth inning a very solid day.

“A healthy John Lackey gives us a huge boost. Not just in terms of number of innings he can pitch, but the performance.”

But innings are important too, and the starters are going deeper into games. Even Doubront has avoided early exits, going two outs into the seventh in each of his last two starts.

Deep starts keep a bullpen fresh and currently the Boston bullpen is very good.

Roster depth. Much is made of Farrell’s return to Boston, but if this Red Sox team continues it run, then second-year General Manager Ben Cherington is a contender for executive of the year.

Cherington built a roster full of pieces for Farrell to use in different situations.

Four pitchers have lost time to injuries — Lackey, closer Joel Hanrahan and lefty relievers Craig Breslow and Franklin Morales. Designated hitter David Ortiz, shortstop Stephen Drew and right fielder Shane Victorino have also missed time.

Farrell has had pitchers and players to fill in and, in most cases, fill in very well.

With Victorino out with a sore back, Daniel Nava played right field and Mike Carp played left on Sunday.

Nava and Carp, the starting corner outfielders? Anyone foresee that scenario back in spring training when both were fighting to make the team?

Nava simply goes 2 for 4 with three runs, and makes two Willie Mays-like catches in the game, one an over-the-shoulder effort, the other a diving grab to end the game.

“Outstanding defense,” Farrell said. “Because of Shane’s situation, he’s our everyday right fielder and we have complete confidence in him. I don’t think twice putting his name in the lineup.”

Carp did not get into a game until a week into the season, and did not make a start until April 16. Carp stayed patient and ready. Now he’s batting .455 (10 for 22) in 11 games. He went 2 for 3 with a walk on Sunday.

“Just prepared every day, treated my (batting practice) as a game,” Carp said. “I’m itching for as many at-bats as I can possibly get, but I understand the concept of the team. We have a very deep bench.”

Farrell has not only been able to interchange parts to fill in for injuries, he’s been able to run out a quality lineup. Heading into Sunday’s game, Boston was second in the league in runs scored.

“Our overall offensive approach has been outstanding, “Farrell said, “very consistent from top to bottom.”

This is a talented team. These players believe April has not been a fluke, but the beginning of something special.

“We got a good group,” second baseman Dustin Pedroia said. “Playing good ball. Doing the right things.

“Hope we can build on this month and keep going.”

Kevin Thomas can be contacted at 791-6411 or at:

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Twitter: ClearTheBases