Kevin YoukilisKevin Youkilis has switched sides in the greatest rivalry in Major League Baseball.

The former Red Sox and White Sox first baseman signed a one-year, $12 million contract with the New York Yankees, according to Ken Rosenthal of FOX Sports. The Yankees needed a third baseman after learning Alex Rodriguez would miss four to six months following hip surgery.

Red Sox Nation surely won’t be happy with Youk, and those YOUUUUK cheers will likely turn into boos when he makes his return to Fenway Park in 2013. Youkilis batted .235 with a .745 OPS in 122 games split between Boston and Chicago in 2012 in what was by far his worst full season in the major leagues. Once Rodriguez returns, Youkilis could DH for the Yankees.