Bruney, handed a two-run lead in the top of the eighth, couldn't hold on as he was booed off the mound after allowing the tying runs to score.
The Yankees, however, scored three times in the bottom of the inning and nailed down their sixth straight win with an 8-5 victory over the Mariners at the Stadium.
Rivera, who notched his 500th save Sunday night, pitched the ninth to record No. 501 and his 19th of the season.
Alex Rodriguez broke a 3-3 tie with one out in the seventh, driving a 2-and-2 pitch from righthander Chris Jakubauskas deep into the leftfield seats to give the Yankees a 5-3 lead. It was Rodriguez's 565th home run, leaving him four short of Rafael Palmeiro for 10th all-time.
Johnny Damon had led off the inning with a double down the leftfield line.
Despite Phil Hughes mowing down the Mariners in order in the seventh, Girardi inserted Bruney in the eighth. Bruney immediately got into trouble, allowing three straight singles and he walked off the mound with the score tied at 5.
"I have no excuses. I was not good tonight,'' Bruney said. "The guys came through and picked me up, though.''
Hideki Matsui started the bottom of the eighth against Sean White with a double to right-center, the first of four straight hits in the three-run inning. Melky Cabrera drove in one run with a double and Derek Jeter brought home two runs with a single to left.
"He's thrived in that situation for us,'' Girardi said of Cabrera's clutch, late-inning hit. "You look at his numbers after the seventh inning, they're very, very good. He's been one of the guys who's been a big contributing factor late in games."
Joba Chamberlain started for the Yankees and pitched decently,
"For him, the key is, stay out of long counts and don't walk people," Girardi said of Chamberlain before the game.
Chamberlain did only one of the two. He walked three - not bad - in 51/3 innings, but consistently was in long counts. He threw 96 pitches - 55 strikes - allowed nine hits and three runs.
"There's going to be days where you don't have your greatest stuff and you have to go out and just compete,'' Chamberlain said. "At the end of the day, you have to be able to keep your team in the game, good or bad, whether you've got your great stuff or you don't."
The Yankees scored two unearned runs off Brandon Morrow in the second.
The Mariners cut it to 2-1 in the third when Ronny CedeÃÂ±o led off the inning with a home run to left, the ninth homer Chamberlain has given up this season.
The Yankees added to their lead in the fourth, though only by one run after having the bases loaded with none out. The run scored on a groundout by Cabrera.
Hughes, scintillating since his move to the bullpen in early June, came in for the seventh and retired the Mariners in order, including getting Ken Griffey Jr. swinging on a 96-mph fastball.
Neverthless, the Yankees went with Bruney.
"Bruney's our eighth-inning guy.'' Girardi said. "We need to get Bruney going."