NEW YORK (AP) – Alex Rodriguez made the New York Yankees forget Kei Igawa’s forgettable debut.

A-Rod hit a grand slam off Chris Ray with two outs in the ninth inning, giving the Yankees a memorable 10-7 victory over the Baltimore Orioles on Saturday.

Mr. Rodriguez homered twice, doubled and drove in six runs. Two days earlier, he popped out with the bases loaded to end the eighth in a 7-6 loss to Tampa Bay, a performance reminiscent of his October flop.

Mr. Igawa left after five mediocre innings trailing 7-3.

But Jason Giambi hit a three-run homer in the eighth off Danny Baez to get the Yankees close. Ray (0-1) got the first two outs of the ninth before Robinson Cano singled, Derek Jeter walked and Bobby Abreu was hit by a pitch.

Mr. Rodriguez then connected on a 1-2 pitch, and knew it was gone as soon as he hit it. The ball landed in the black section of the bleachers in center for his 14th career slam and, after Mr. Rodriguez reached the dugout, Jeter shoved him back on the field for a curtain call.

Mariano Rivera (1-0) got the win with a one-hit ninth. Melvin Mora tied a career high with five RBIs for Baltimore,

Two days after Daisuke Matsuzaka pitched seven dominating innings to win his debut for the Boston Red Sox, Mr. Igawa started hearing boos after his 12th batter. He failed to string together a 1-2-3 inning and gave up seven runs, eight hits, three walks, a hit batter and two home runs, a performance that left him with a 12.60 ERA.

Nick Markakis hit an opposite-field homer into the left-field seats in the first inning off the 26-year-old left-hander with the Beatles-like mop top. After Mr. Rodriguez put New York ahead with a two-run homer in the bottom half, Mr. Igawa gave up four runs in the second.

Brian Roberts walked with the bases loaded to force in the tying run, one pitch after first base umpire Jerry Layne ruled he checked his swing on a 2-1 offering. Mr. Mora blooped a three-run double down the right-field line, with Mr. Abreu making a poor throw to second as the third run came home, and Mr. Igawa bobbled Markakis’ nubber in front on the mound for an error, prompting a round of boos. Only a diving catch by first baseman Doug Mientkiewicz on Mr. Igawa’s late throw prevented another run.

Mr. Mora added a two-run homer in the fourth for a 7-2 lead, causing another round of jeers from the disappointed crowd of 50,510 on a 39-degree afternoon. Mr. Igawa, who received three mound visits from pitching coach Ron Guidry, walked very slowly toward the dugout after retiring his final batter.

New York paid $26 million for Mr. Igawa’s rights and signed him to a $20 million, five-year deal, just after the Red Sox bid $51 million for Matsuzaka and agreed to a $52 million, six-year contract. While Mr. Matsuzaka is viewed as an ace, Mr. Igawa is a back-end of the rotation pitcher.

“He really can’t concern himself with some other team and some other pitcher,” Yankees manager Joe Torre said before the game. “Hopefully, he’s not doing the comparing as much as maybe people in Japan or the media.”

While Dice-K throws 95 mph and has a commanding array of pitches, Mr. Igawa topped out at 91 mph and usually was around 89.

“I’d like to believe that both of them have pitched long enough to understand what they’re comfortable doing,” Mr. Torre said.

Hideki Matsui, the Yankees’ other Japanese player, left in the fourth inning with a strained left hamstring.

Steve Trachsel, making his debut with the Orioles after six seasons with the New York Mets, gave up four hits in 6 2-3 innings, allowing his only runs on A-Rod’s second homer of the season and Jorge Posada’s RBI single in the fourth.

Baltimore signed Mr. Trachsel in mid-February, only after Kris Benson got hurt.

Mr. Igawa made it four wipeouts in a row for the Yankees’ starting rotation, with Carl Pavano, Andy Pettitte and Mike Mussina also failing to win. New York’s starters have allowed 22 runs – 19 earned – and 28 hits in 17 1-3 innings for a 9.87 ERA. If they don’t improve, the Yankees could step up efforts to sign Roger Clemens or call up top prospect Phil Hughes.

Notes:@ Mr. Mora’s previous five-RBI game was against the Yankees on Sept. 27, 2005. … With the injury to Mr. Matsui, Miguel Cairo took over in left – just his fifth outfield appearance since 2003. Johnny Damon still recovering from a strained right calf, pinch hit in the eighth and struck out, then went to center, with Melky Cabrera shifting to left. … Mr. Cabrera singled softly to center in the seventh, ending an 0-for-10 slide at the start of the season.