New York ? Brandon Backe was at his best with runners on base. Good thing, too, because he put them there.

Backe worked around a career-high six walks, and pinch-hitter Orlando Palmeiro homered to lead the Houston Astros past the New York Mets, 4-1, Wednesday night.

“The amount of changeups that worked for me tonight really helped me out,” Backe said. “I just stayed away from the big inning. If I did walk a guy, I somehow got a strikeout or a groundball. I refocused and went after the next hitter.”

Craig Biggio and Jason Lane each had an RBI double for the Astros, who improved to 6-23 on the road and handed the Mets only their fourth defeat in 12 games.

New York lost catcher Mike Piazza to a bruised left wrist in the first inning after he was hit by a foul ball. X-rays were negative, and he was day-to-day.

“It’s swollen, but we’ll just go and see how it is tomorrow,” Piazza said. “On the base of the wrist, the left wrist, pretty flush, pretty square. I’ve had it on ice two or three times. Right away, it was bugging me, and I just tried to get through the inning.”

Piazza’s replacement, Ramon Castro, came through with an RBI double in his first at-bat, but Backe (6-3) limited the damage.

Starting on three days’ rest after making his first relief appearance of the season Saturday against St. Louis, the right-hander gave up four hits in six innings. He struck out seven, helping him overcome a wild outing.

“He’s been such an unusual study so far. He’s pitched so well at home, and he hasn’t pitched as well on the road. But you’ve got to hand it to him today. He made the pitches when he needed to,” Houston manager Phil Garner said. “It doesn’t matter how you do it, pretty or ugly, just get it done.”

Chad Qualls and Dan Wheeler each threw a scoreless inning before Brad Lidge got three outs for his 14th save in 16 chances.

One night after Pedro Martinez pitched a gem against one of baseball’s worst offenses, Mets starter Victor Zambrano (3-6) allowed three runs and six hits in six innings.