BOSTON — If this week is going to be the biggest test yet for the Red Sox, the team passed its first exam with flying colors last night.

The Sox put aside their American League East rivals for the time being and began a week of meetings with two first-place teams by easily beating Detroit, 7-1.

It was a terrific night for the Fenway faithful, made all the better because the star was the prized newcomer, Daisuke Matsuzaka.

After struggling in his first three Fenway starts (a 7.58 ERA), Matsuzaka showed why the Sox shelled out more than $100 million to get him. He gave the Sox their first complete game of the season, allowing six hits, with no walks and five strikeouts.

He threw 124 pitches, 86 for strikes, as he ran his record to 5-2.

“He didn’t look like he needed to come out,” said Sox manager Terry Francona. “He was better at the end than he was at the beginning.”

Matsuzaka, who is still adjusting to the different philosophy in the United States from what he was used to in Japan, said he has made some changes in his preparations for games.

“The fact that I was able to pitch my first really good game is what I am excited about,” he said. “I’m conscious of the pitch count, but that doesn’t mean I have to change the way I’m pitching.”

He had plenty of help.

Offensively, the Sox pounded out 13 hits. David Ortiz and Julio Lugo were the keys.

Ortiz entered only 1-for-14 in his career against Detroit starter Nate Robertson. After the Tigers had taken a 1-0 lead in the top of the third on Curtis Granderson’s seventh home run, Ortiz singled in Kevin Youkilis, who had doubled, to tie it in the bottom of the inning.

It was 2-1 in the fifth when Ortiz doubled and scored on a single by Manny Ramirez. Boston broke it open with four in the eighth off reliever Bobby Seay, with Lugo delivering a bases-loaded triple.

Add some sharp defense, including two diving plays by second baseman Dustin Pedroia, one going in each direction, and it was an excellent start to a big week for the Sox.

This week should give Sox fans more answers on just how good their team is. They’ve been beating up on their East Division rivals, but it is obvious the East is not as strong as most expected it would be.

This week it is the first-place Tigers from the A.L. Central followed by the first-place Braves from the National League East.

The Sox used the change to provide more evidence why they have the best record in baseball as the teams near the quarter pole.

Detroit came in with the second-best record in the American League and it looks to be ready to make a strong defense of the American League title it won last season. The Tigers were a surprise when they won the pennant last season. But they are not that way any more. They look to be at least as good, if not better, than last season.

They are as balanced as any team in the majors. They have the complete package. They talked Jim Leyland, now 62, out of retirement last year and he has only built on his reputation as one of the game’s very best managers. In Dave Dombrowski, they have one of the most respected, as well as one of the most successful general managers in the game.

The roster is a nice blend of veteran and young talent. It was the emergence of young starters Jeremy Bonderman, now 24, Justin Verlander, also 24 and Robertson, last night’s loser, that catapulted Detroit to the top last season.

But there is a ton of veteran talent, too, led by Pudge Rodgiguez, Maglio Ordonez and pitcher Kenny Rogers, who is now on the disabled list.

With the unbalanced schedule this is Detroit’s only trip to Fenway in the regular season. The Sox go to Comerica Park only once.

Detroit is strong. But as the Sox showed last night, they are, too. With each passing day it appears more and more clear that Boston is not going to be left out of the October fun this season.

pkenyon@projo.com