Richie Zisk drove in three runs with two homers and a single to lead Seattle to victory in New York.
Zisk had just returned to the lineup after three weeks on the bench with a pulled muscle in his rib cage.
"The frustration of being injured is not something I like to cope with," said Zisk, who has had six knee operations since he was 13 years old.
"I love the game of baseball, but time catches up with you," he said, adding that he worries about another knee injury. "I'm one behind (pro hockey's) Bobby Orr and five behind (pro football's) E.J. Holub, and I don't intend to catch up with either one of them."
The Yankees fielded shabbily. Right fielder Oscar Gamble allowed Al Cowens' single to skip between his legs in the second inning, then, in the third inning, third baseman Graig Nettles let Steve Henderson's grounder go between his legs for a two-base error.
Winner Jim Beattie (4-3), who pitched for the Yankees in 1978-79, yielded two runs on eight hits in 7 2/3 innings.
The Yankees got more bad news: relief ace Rich Gossage was unavailable for yesterday's game with the Mariners because of a slightly pulled rib cage muscle in his right side.
His status will be judged day to day, a Yankees spokesman said.