BOSTON — Boston rookie third baseman Will Middlebrooks went out of his way to try to avoid sounding overconfident, considering he has become a hot topic of conversation in a fight for a regular starting spot. Middlebrooks had a solo homer among his three hits and drove in two runs, Franklin Morales gave Boston another decent start as the fill-in for Josh Beckett, and the Red Sox beat the Atlanta Braves 8-4 on Saturday night. Middlebrooks, recalled from Triple-A Pawtucket when Kevin Youkilis went on the disabled list with a strained lower back on May 2, has put up big numbers in a small period of time.