They'll meet Friday night at Dodger Stadium for the first time since that blockbuster deal.
The Red Sox (75-54) hold a one-game edge over Tampa Bay for the AL East lead, while the Dodgers (75-52) have virtually run away with the NL West after building a 9 1/2-game lead over Arizona.
Before Boston finished 69-93 last season - its worst mark since 1965 - it dumped more than $250 million in payroll by sending Adrian Gonzalez, Carl Crawford, Josh Beckett and Nick Punto to Los Angeles in exchange for James Loney, Rubby De La Rosa, Ivan DeJesus Jr. and Jerry Sands on Aug. 25.
Loney, DeJesus and Sands are no longer with the organization, while De La Rosa's contributions have been minimal. However, the salary relief gave Boston more wiggle room to reach offseason agreements with free agents Shane Victorino, Stephen Drew, Ryan Dempster and Koji Uehara, not to mention the re-signing of David Ortiz to a two-year deal.
Beckett's season is done after neck surgery, but Crawford and Gonzalez have made big contributions for Los Angeles, which is 45-10 since June 22 and 23 games above .500 for the first time since 2009. Crawford's .291 batting average is his best since 2010 with Tampa Bay, while Gonzalez, batting .370 over his last 11 games, leads the team with 16 homers and 77 RBIs.
"This is one of those deals that has helped both sides, clearly," Boston manager John Farrell told the team's official website.
Both also have been among baseball's best in interleague play this year, with Boston going 11-4 and Los Angeles going 11-6.
"The better teams continue to force you to be better," Dodgers manager Don Mattingly told the club's website. "I look forward to it a little bit."
The Dodgers' surge has been bolstered by strong pitching, particularly during a 10-2 stretch with starters posting a 1.86 ERA.
Following Clayton Kershaw's strong eight innings in a 6-0 win at Miami on Thursday, Ricky Nolasco (9-9, 3.60 ERA) takes the mound for Los Angeles. He's 4-1 with a 2.98 ERA in eight starts since being acquired from the Marlins, including 3-0 in six outings since the All-Star break.
Nolasco struggled the last time he saw the Red Sox, surrendering nine runs and nine hits in 3 1-3 innings of a 15-5 loss June 20, 2012.
He'll try to cool off Will Middlebrooks, who homered in a 12-1 Boston win at San Francisco on Wednesday and is batting .441 with seven RBIs in 11 games since being recalled from Triple-A Pawtucket.
Ortiz exited in the fifth inning with lower back tightness but is expected to play Friday, according to the team's official site.
John Lackey (8-10, 3.22) gets the ball for Boston after ending a five-start winless streak Saturday when he gave up one run over 6 2-3 innings in a 6-1 victory over the New York Yankees. His 15 quality starts lead Boston, but he's received no runs of support five times and three or fewer on eight other occasions.
Lackey is 5-2 with a 1.89 ERA in nine starts against the Dodgers - all while with the Angels - but hasn't faced them since a 2009 defeat.
Boston is batting .318 and averaging 5.9 runs in interleague play - both the best marks in the majors - and the top two AL batting averages in interleague play this year belong to Victorino (.455) and Jacoby Ellsbury (.438). Victorino, 11 for 22 over his last five games overall, is slugging .750 in 11 contests against the NL, while Ellsbury has scored 16 runs in 15 interleague games.
Crawford has hit .467 (21 for 45) off Lackey - tops among players with at least 30 at-bats against him - while Gonzalez has gone 6 for 14.
Victorino is just 6 for 37 with seven strikeouts against Nolasco. Stephen Drew is 11 of 21 with three home runs, three doubles and a triple versus the right-hander.