CC Sabathia
New York Yankees ace starting pitcher C.C. Sabathia will opt out of his contract and become a free agent, according to Sports Illustrated's Jon Heyman on his Twitter feed. Reuters

Yankees-Red Sox series are always entertaining, and the two teams seem particularly well matched going into this three-game set, which starts tonight. New York holds a slim one-game lead over Boston in the American League East, but the Red Sox have taken five of the two teams' six meetings thus far this season. Here are three things to watch in the newest installment of their century-old battle:

The pitching matchups slightly favor Boston. Although the Yankees hit well against Jon Lester, the lefty is 7-2 on the year--but with a middling WHIP (1.35). On the other hand, Freddy Garcia has a comparable WHIP and scares no one. Tim Wakefield has found his groove--and so has his counterpart on Wednesday, A.J. Burnett. Teixeira enjoys hitting Wakefield, as does Alex Rodriguez, but the Sox might like facing Burnett even more--to the tune of 24 RBIs during their encounters in the last five years, according to ESPN. The aces battle on Thursday--Josh Beckett against CC Sabathia, and although Beckett is the AL leader in ERA, who hits CC these days? No one.

Home runs (lots for the Yankees). This edition of the rivalry will take place in the homer-friendly confines of Yankee Stadium, and the Yanks love the longball. They lead the majors with 88--16 more than the next closest club, Texas. Look at their batting averages, and New York looks unimpressive. Look at their OPS (on-base percentage plus slugging percentage) and they are .779 as a ball club. But Boston is only .002 behind them in team OPS.

Jorge Posada is sitting. Derek Jeter will perform designated hitter duties tonight, with Eduardo Nunez covering shortstop. Two right-handed pitchers follow Lester tonight, so we'll see if New York is committed to Posada at DH when the lineups for Wednesday and Thursday are announced. The official stance of the Yankees is that Posada will not be their DH when the team faces a lefty.