Clay Buchholz was pushed back again from a tentative Sunday start against the Orioles, but he will pitch on Tuesday. Maybe. The Red Sox cannot quite say for certain that Buchholz’ sore neck, which was feeling better yesterday, will improve enough to throw a full bullpen session on Sunday and then be good to go in one of the games of the doubleheader against the Rays at Fenway next Tuesday. “I wish I could say it’s going to be a concrete thing for Tuesday,” Sox manager John Farrell said before last night’s 5-4, 13-inning loss to Baltimore. “We feel like two additional days will be time to get over the soreness. But we won’t put him out there until he’s symptom-free.” Farrell said that Buchholz’ AC joint is not part of the problem, but that soreness in the base of the neck muscle on his right side is lingering. Jon Lester will pitch Sunday on his normal four days’ rest even though the team was hoping Buchholz would be able to go so that Lester, who has been struggling, could get two extra days of rest because of the off day Monday. If Buchholz does pitch, the club will need another starter. Alfredo Aceves, who pitched so well in his spot start Wednesday night in St. Petersburg, is a strong candidate. Rubby De La Rosa was another, but with his start washed out last night at Triple-A Pawtucket, that probably eliminates the ex-Dodger from contention.