Trailing 6-4 with two outs in the ninth, Bobby Abreu hit an RBI double, Torii Hunter was walked to load the bases and Guerrero singled to center field off reliever Jonathan Papelbon, scoring Chone Figgins and Abreu.
The Angels, who trailed 5-1 through four innings, move on to the American League Championship Series against the New York Yankees, a 4-1 winner over the Minnesota Twins in another series sweep. Game 1 is Friday at New York.
Kendry Morales hit a solo homer and Juan Rivera had a two-run single for Los Angeles.
J.D. Drew slugged a two-run home run, Dustin Pedroia had a two-run double, and Victor Martinez and Mike Lowell contributed run-scoring singles for Boston.
Copyright 2009 by United Press International.