Ichiro singled off Workman, stole second and was moved to third on a Vernon Wells sac-fly.
Workman's issues in the ninth spoiled another splendid performance from Jon Lester, who worked eight innings, allowing 10 hits and three earned runs while striking out six.
Will Middlebrooks homered off Rivera in the ninth to tie the game at 3.
What they'll be saying: The Red Sox had every right to take their foot off the gas in this one as they had the best record in MLB heading into the game Sunday and an eight-game lead in the AL East. Lester and Middlebrooks did everything in their power to complete the sweep over their arch-rivals, but this was certainly a game the Red Sox could afford to lose.
Red Sox fans should be more confident than ever coming out of this series with New York as Boston continued to add to its World Series resume. Timely hitting was ever apparent this weekend and Lester made another strong pitch to be considered the Game 1 starter for the Sox in a playoff series.