Boston – The Athletics have acquired ace pitcher Jon Lester from the Red Sox in a deal that will send slugger Yoenis Cespedes to Boston, a source told ESPNBoston.com’s Gordon Edes.

The Athletics also will receive outfielder Jonny Gomes while the Red Sox will get Oakland’s competitive balance draft pick, according to the source.

The deal marks the end of Lester’s storied stint with the Red Sox, who won two World Series with the left-hander at the top of their rotation.

The 30-year-old Lester, Boston’s lone All-Star this season, is 10-7 with a 2.52 ERA this season.

Lester, who is scheduled to become a free agent after this season, had publicly stated his desire to remain with the Red Sox. But contract negotiations stalled this past offseason, when Lester reportedly turned down Boston’s four-year, $70 million offer.

Lester will join a star-studded Athletics rotation that already includes All-Stars Jeff Samardzija and Scott Kazmir and promising youngster Sonny Gray.

But the Athletics paid a hefty price for Lester in Cespedes, the two-time reigning Home Run Derby champion who has 17 homers and 56 RBIs this season.

I don’t know about anyone else, but this is kind of a relief. I would have liked them to keep Lester for the rest of this year and resign him, but he’s wasting the rest of this year here, and eventually the offers from contending teams were going to be too good to pass up. So you lose Lester for the rest of this year, and you hope you can convince him to resign in the offseason. Anyone who says the Red Sox are completely out of the race to resign him are high, especially with everything Lester has gone through in Boston. He loves Farrell. He loves Pedroia. He loves Ortiz. He might get more money elsewhere, but the Sox will be at the top of the list. On the flip side, we fill a huge void in our lineup with a power hitting, uber fielding outfielder in Yoenis Cespedes. You wanted the Sox to get someone proven in return for Lester, and that’s exactly what they did. It hurts losing Gomes, who at this point is more a clubhouse guy than a good player, and Lester was our ace, but that’s the business of baseball. I’ll never forget the no hitter. I’ll never forget him dominating the postseason last year. He was a warrior, and I hope he’s back in Boston soon. Also, the A’s rotation is kind of unfair now. They could trot me out in LF and win a few playoff series.

In the meantime, this is going to be nice to get used to:

– Ryan