The Jays’ Frank Thomas, left, and Vernon Wells celebrate their win over the Red Sox.

AP / Lars Hagberg

TORONTO — He was dominant. And then he wasn’t. And then he was again.

Unfortunately for Daisuke Matsuzaka and the Boston Red Sox, the right-hander’s sudden and unexpected lapse of concentration and command in the fourth inning cost the team dearly in a 2-1 loss to the Toronto Blue Jays last night at the Rogers Centre.

A hot one-hop smash, a potential inning-ending double-play ball that shortstop Julio Lugo was unable to handle in the pivotal inning, didn’t help matters. That ball, which ticked off Lugo’s glove, went for an RBI single for Lyle Overbay, tying the score at 1-1.

But, finally having to pitch out of the stretch after three near-perfect innings, it was Matsuzaka’s uncharacteristic wildness that produced three walks in a four-batter span, the last of which, to Gregg Zaun, forced home the tie-breaking run.

And after keeping it a one-run game by whiffing Royce Clayton and retiring Jason Smith on a long fly ball, leaving the bases filled, Matsuzaka found his form again. He was spotless in the fifth and sixth, fanning four more, running his total to 10 before manager Terry Francona elected to pull Matsuzaka, telling him to call it a night after 105 pitches.

Matsuzaka’s record fell to 1-2, though his earned-run average is still a solid 2.70. He has been given five runs of support in three starts, including Wily Mo Pena’s monster solo homer off winner Gustavo Chacin in the third inning last night.

“He (Matsuzaka) had temporary amnesia for a couple of minutes,” said Francona. “He was so good before and after.”

Mechanically, Matsuzaka seemed to lose it.

“He just seemed to rush a little bit,” said Sox pitching coach John Farrell. “By no means is it a flaw, but he lost his release point and threw 40 pitches (38, actually, after having thrown only 39 through three innings).

“He was dominant throughout except losing his release point for those four batters (three walks and Overbay’s hit). The perplexing thing is he walked three batters that inning and then he came back, got locked in and threw only six balls the next two innings,” added Farrell.

Matsuzaka said his problems began with one out in the fourth after Vernon Wells barely beat out an infield roller to third baseman Mike Lowell, who made a nice barehand pickup and strong throw to first.

To that point, Dice-K had thrown only two pitches out of the stretch all night, after Jason Smith’s two-out single in the third. Smith was the first batter to reach against Matsuzaka.

Matsuzaka, aware that Wells had to be held close, lost his rhythm trying to throw quickly to the plate with Frank Thomas up.

“I got a little over-conscious of Frank Thomas’s at-bat,” said Matsuzaka through interpreter Msas Hoshino. “I lost a little bit of control.”

Matsuzaka, who overmatched Thomas, the Jays’ designated hitter, with strikeouts in the second and sixth innings, was nowhere near the strike zone in this at-bat. He walked Thomas on four pitches, missing badly with his fastball, up and in.

Then came the Overbay at-bat. It could have been an inning-ending double play. That’s what Matsuzaka seemed to think as he saw the ball leave Overbay’s bat.

“As a pitcher in that situation, to hit a grounder to shortstop is what I expected, but the runner was overlapping the shortstop so it wasn’t an easy play,” said Matsuzaka.

But he seemed to admit that the double play not turned — it was a tough play, but one the Sox saw routinely last year when Alex Gonzalez played short — rattled Dice-K because he walked the next two hitters and Boston suddenly was trailing, 2-1.

“I can’t argue against the fact that’s how it appears,” said Matsuzaka.

After those two walks, and with Kyle Snyder warming up, Matsuzaka was able to keep the damage to two runs.

“Obviously, I was disappointed in myself (at walking home the tie-breaking run), but I told myself not to let any more runs score and have faith in my teammates (to score more runs),” he said.

That, though, didn’t happen. Chacin, now 6-0 lifetime against the Sox, nicely spaced six hits in 6 2/3 innings and the Sox were unable to dent relievers Casey Janssen and Jason Frasor in dropping the first game of this three-game set, which also dropped Boston out of first place in the American League East, a half-game behind the Blue Jays.

skrasner@projo.com