Kaz Matsui has had a tough transition from Japan to America, troubled by errors in the field that forced a switch in positions and a sinking batting average that caused the Mets to drop him to eighth in the lineup. He’s been booed endlessly by Shea Stadium fans, who show little patience for failure.

For one game, though, Matsui turned the hoots to howls with a two-run homer in the seventh inning that gave the Mets a 2-1 victory over the Cincinnati Reds last night.

“The home run was very big for me,” Matsui said through a translator. “The at-bat gave me more confidence because of the result I got.”

Matsui and Japanese left-hander Kaz Ishii provided an exclamation point for Asian Night at Shea, which began with karate demonstrations on the field and finished with some late-inning heroics by the Mets.

Cincinnati starter Ramon Ortiz (1-2) handcuffed the Mets through six innings and was leading 1-0 on a run the Reds scored against Ishii without benefit of a hit. Then in the seventh, Doug Mientkiewicz singled with one out and, after David Wright flied out, Matsui hit Ortiz’s 1-1 pitch over the right-field wall to turn the game.

Matsui had two hits on Monday night and was feeling good at the plate.

“The last couple of games, I’ve had good at-bats,” he said. “The first two times up today, I didn’t feel all that bad. The third at-bat, I was happy to hit it out of the park.”

Ishii, making his first start after a month on the DL, allowed just three hits over 6 1 /3 innings, but walked Ryan Freel leading off the sixth and it cost him. On a hit-and-run play, Freel reached second as Felipe Lopez grounded out. Then Freel stole third on the first pitch to Sean Casey. With the infield drawn in, Casey hit a high hopper to first and Freel scored.

It looked like that might be enough for Ortiz, who spent three weeks on the DL in April with a groin injury and came in with a 6.75 ERA. Against Matsui, Ortiz said he left a little cutter inside and it cost him.

After Matsui’s homer put the Mets ahead, Roberto Hernandez pitched a scoreless eighth. With three lefties due up for the Reds, manager Willie Randolph brought in his only lefty reliever, Dae-Sung Koo.

“That’s why he’s here – to get lefties out,” Randolph said.

Koo got one of the three and left with runners on first and second. But Mets closer Braden Looper relieved and got Joe Randa to fly out and struck out Austin Kearns to finish for his 10th save.

The win went to Mike DeJean (3-1), who got two outs in the seventh.