While Lester tries for a third consecutive win, Ortiz appears ready to come off the disabled list when the Red Sox look to avoid matching a season high with a fifth straight defeat Friday night against the visiting Kansas City Royals.
Out since suffering a strained Achilles on July 16, Ortiz could be activated Friday after he ran the bases without pain prior to Thursday's 14-13, 10-inning loss to Los Angeles. The slugger was hitting .316 with 23 homers and 58 RBIs at the time of his injury.
"It looked like David got through everything perfectly (Thursday)," manager Bobby Valentine told the Red Sox's official website. "If he gets through (without problems), we're planning on hopefully activating him (Friday)."
That would obviously be a huge boost for Boston (59-66), which is 13 1/2 games behind AL East-leading New York and 8 1/2 out of the second wild-card spot. The Red Sox blew a 6-0 lead Thursday, then rallied from deficits of 8-7 in the sixth and 12-11 in the ninth before losing for the 15th time in 21 games.
"We need to try and find a way to win these," said second baseman Dustin Pedroia, who went 4 for 6 with five RBIs. "We are playing hard, but we need to find a way to be one run better.''
Though Boston dropped two of three at Kansas City (55-68) in May, it has won 11 of 16 at home against the Royals.
Lester (7-10, 5.03 ERA) has allowed one run in each of his last two starts after he went 0-5 with a 7.49 ERA in his previous seven. He gave up a homer and four other hits in seven innings of a 4-1 win over the Yankees on Saturday.
"It's been a grinding season,'' said Lester, who's 0-5 with a 9.33 ERA in his last five starts at Fenway Park. "I said back a month or so ago, I'm not giving up. Keep working hard, and things will turn. The last handful of starts I feel like they have.''
The left-hander is 5-2 with a 1.35 ERA in eight starts against the Royals, but allowed four runs - one earned - in five innings of a 4-3 loss at Kansas City on May 9.
Royals starter Bruce Chen (9-10, 5.45) gave up three runs in 6 2-3 innings of that contest while improving to 3-5 with a 6.30 ERA in 10 starts versus Boston. Chen, however, allowed 10 runs in four innings of his most recent start at Fenway, a 12-5 loss July 27, 2011.
The left-hander gave up a two-run homer in six innings of a 9-4 win at Chicago on Saturday. He is 2-1 with a 4.00 ERA since going 0-3 with an 8.73 ERA in his previous seven outings.
"He's doing fine, he made good adjustments," manager Ned Yost told the Royals' official website. He's doing a great job with it and the results have shown that. He's pitched great his last three or four times out."
Though Ortiz hit a grand slam off Chen at home last season, he is 4 for 21 against him. Pedroia is 4 for 7 with a double and home run against the 35-year-old.
Kansas City outfielder Jeff Francoeur is batting .333 (12 for 36) with a homer in nine games at Fenway Park, but is 1 for 10 versus Lester. Alex Gordon is 0 for 11 with 6 strikeouts.
The Royals head to Boston after totaling five runs while losing two of three at Tampa Bay.