"That is significant," manager Joe Torre said. "It's all based on pitching."
Tino Martinez homered in his third consecutive game for the $200 million Yankees (14-19), who were coming off consecutive shutouts of Oakland. It was the longest New York had gone into a season without winning three straight since 1925, when it took 97 games.
Adrian Beltre connected for the Mariners, who have lost eight of nine.
Ichiro Suzuki went 2-for-4 with an RBI single and a strikeout against Johnson, his first regular-season at-bats against the Big Unit.
After missing his previous scheduled start because of a stiff groin, Johnson (3-2) gave up seven hits and two walks against Seattle, striking out seven in his 249th win.
Even though the Big Unit was already over 100 pitches, Torre wanted to stay with Johnson in the eighth.
"Any time Randy Johnson pitches, you feel you've got to win," Torre said. "I just thought he deserved the opportunity to win or lose the game himself."
On his 119th pitch, the 6-foot-10 left-hander struck out slumping Bret Boone with two on to end the eighth.
"He buries that slider, it's tough. It's the best pitch he threw me all night," Boone said. "It's a tough pitch to lay off. Earlier in the at-bat, he gave me a pitch to hit and I missed it."
Pinch-hitter Rey Sanchez opened the bottom half with a single off ex-Yankee Jeff Nelson (0-1) and advanced on Derek Jeter's sacrifice bunt. Womack then bounced a single up the middle, giving New York a 4-3 lead.
Boone had just been shifted over at second base, leaving him no chance to make the play.
"It hit the plate and did something -- bounced over my head, bounced to the left," Nelson said.
Mariano Rivera worked a perfect ninth for his fourth save in six chances, giving the Yankees three wins in a row for the first time since their historic collapse in last year's AL championship series, when they took a 3-0 lead against Boston only to lose the next four.
New York's pitching is getting healthy against the punchless Athletics and Mariners, who began the day with the two lowest slugging percentages in the majors.
"We're starting to put a few things together," Womack said. "I think it's a key for us, not giving those guys a jump and playing from behind all the time. That's what the pitching is doing for us."
The Yankees skipped Johnson's previous turn because of his left groin -- and he wasn't happy about it.
In the first inning Monday, he appeared to reach for his groin after a pitch to Richie Sexson, bringing head trainer Gene Monahan and Torre to the mound.
The Big Unit looked peeved by the visit, speaking sternly before Monahan and Torre returned to the dugout. Sexson then hit a long drive to deep left-center, but Hideki Matsui made a nice running catch to save a run.
"I had a little twinge in the first inning, and I kind of backed off. But in the seventh and eighth innings, I felt really good," Johnson said. "It loosened up as I went along."
Matsui's RBI single off Gil Meche in the bottom half gave New York a 1-0 lead.
Johnson walked No. 9 batter Wilson Valdez in the third. He stole second, went to third on Suzuki's infield single and scored on a sacrifice fly by Randy Winn, ending New York's scoreless streak at 20 innings.
Alex Rodriguez doubled with two outs in the fourth, and Martinez drove a 2-2 pitch over the right-field fence for his fifth homer in 17 at-bats.
"We didn't really plan on numbers from Tino. You look up there and he's got seven home runs," Torre said. "He has that good stroke going. He seems comfortable at the plate."
Valdez sparked the Mariners again in the fifth, hitting a two-out double and scoring on Suzuki's soft single to left. Johnson then picked Suzuki off first base.
Beltre's third homer of the season tied it at 3 in the sixth.
- Johnson has not given up a first-inning run in 15 starts dating to last season.
- Rodriguez grounded into an inning-ending double play on a 3-0 pitch in the first.
- Johnson shut out Seattle 6-0 and struck out 10 in his only other start against his former team, on July 20, 1999, with Arizona at Safeco Field.
- Boone has 999 career RBI.
- This is Seattle's only trip to Yankee Stadium this season. The Mariners are 9-9 on the road and 4-10 at home.
- Suzuki has faced Johnson twice in All-Star competition, going 1-for-2 with a single, according to the Elias Sports Bureau.
- Seattle is 1-8 against left-handed starters.
- Meche allowed three runs and six hits in 6 2/3 innings.
- Jason Giambi went 0-for-3, dropping his average to .195.