TORONTO — Like some mad scientist tinkering in his laboratory, Daisuke Matsuzaka has been working overtime to find just the right formula.

In his side sessions between starts, Matsuzaka worked on his tempo, his mechanics and his command, pushing himself to address the flaws that led to 17 runs over 18 innings in his last three starts.

Evidently, he found something. In his best start in weeks and arguably his finest since his first, Matsuzaka pitched seven brilliant innings last night and limited the reeling Toronto Blue Jays to one run on four hits.

Given ample backing by a lineup that has seemingly rediscovered its power stroke, Matsuzaka and the Red Sox cruised to an easy 9-3 victory. For the second straight night, the Sox cracked four homers, giving them eight in the two-game series.

The Sox have outscored the Jays, 18-5, the numbers evidence of two teams heading in opposite directions. For the Sox, it was their third straight win and seventh in their last nine games. The Blue Jays, meanwhile, dropped their eighth in a row and fell 9½ games behind the Sox in the A.L. East.

Matsuzaka, meanwhile, improved to 4-2. He struck out eight and walked three. The only run against him was a solo homer by Lyle Overbay in the sixth.

“I thought he used all his pitches,” said manager Terry Francona. “He had good command of his fastball and located well. He executed his pitches. (Tonight) he wasn’t forcing the issue. He trusted his ability and was confident. He worked hard this week and it paid off.”

Much of the work had centered around Matsuzaka’s mechanics while pitching out of the stretch, and he got a chance to work on that almost immediately when Alex Rios (four hits) led off the Toronto first with a single.

Matsuzaka got two quick outs before pitching around Frank Thomas and issuing a walk, then got out of the inning by getting Troy Glaus to pop out to second.

After the first, the Jays had more than one baserunner in an inning only once. From the second through the seventh, he retired 18 of the final 24 hitters he faced.

“I made some (mechanical) adjustments,” said Matsuzaka. “I think it’s too early to tell if that made all the difference, but I do hope that with small, incremental changes, this will lead to gradual improvements over time.”

Though he walked three, that total was the lowest in his last three starts.

“My goal going into the game,” he said, “was to limit the number of walks and get ahead in the count. I’m not quite satisfied with my command to this point, but I think there was improvement over the last few starts.”

Opposed by fellow countryman Tomo Ohka, marking only the fourth head-to-head matchup of Japanese-born pitchers in major-league history, Matsuzaka outclassed the former Red Sox righty.

Ohka limited the damage to a single run in the first despite the fact that he walked three and threw a wild pitch. The Sox tacked on two more runs against him in the second thanks to yet another walk and Ohka’s own miscue when he mishandled Dustin Pedroia’s bunt attempt for a base hit. Still, the Sox had stranded four runners after just two innings, three of those in scoring position.

In the fifth, when Ohka walked his fifth hitter and followed that by allowing a single to Mike Lowell, he was done.

The Sox then got their power game going in the sixth when Julio Lugo drove a pitch out to left-center, scoring Pedroia. Three batters later, Manny Ramirez hit his sixth of the season, with the bases empty.

In the eighth, David Ortiz lined a bullet down the right-field line for a two-run shot, capping a four-hit night. Finally, Mike Lowell hit his second homer in as many nights in the ninth, his fourth in six games against Toronto. Of Lowell’s six homers this season, all except two have come against the Blue Jays.

Brendan Donnelly pitched a scoreless eighth before the Jays collected two garbage-time runs in the ninth, including Overbay’s second homer of the night — off Joel Pineiro.

smcadam@projo.com