Called on to pinch-hit in a tie game with one out and the bases loaded, Martinez made the most of his opportunity, drilling a go-ahead three-run double to left-center field that gave Boston a lead it wouldn't relinquish in a 7-5 win over Baltimore at Fenway Park.
The Red Sox maintained their two-game lead in the American League Wild Card standings over the Rangers, who trounced the Indians in a 10-0 laugher on Wednesday afternoon.
Billy Wagner fired a perfect top of the seventh inning to collect his first career American League victory and Jonathan Papelbon nailed down a four-out save for Boston (81-58), which won both games of the two-game set against a Baltimore club it has defeated in 13 of 14 meetings at Fenway dating back to July 12, 2008.
Nearly 24 hours after learning he would not start on Wednesday, Martinez dialed up the drama in extending his hitting streak to 12 games.
"I told him [Tuesday] night in about the eighth inning [that he wasn't starting on Wednesday]," Francona said. "I told him I wasn't going to answer my phone. I said, 'Don't even try.' He fought me a little bit, which I actually really like, but I thought it was in his best interest not to play [Wednesday]."
Martinez thought differently -- and showed it.
"I'll take it," said Martinez, who was acquired from Cleveland at the July 31 non-waiver Trade Deadline. "Any time you help your team get a really important win, it's nice."
A four-pitch walk to Mike Lowell packed the sacks with one out for Martinez, who came to the plate against Danys Baez with one thing on his mind.
"I told myself, 'He's going to throw a strike right here,'" Martinez said. "I just looked for a good pitch to hit, didn't try to do too much and put a good swing on the ball. That's what I did. When you put a good swing on the ball, anything can happen."
The switch-hitting slugger is 11-for-27 (.407) in his career as a pinch-hitter and 6-for-12 (.500) with 15 RBIs with the bases loaded this season.
"He's just a good hitter," Francona said. "I think he enjoys that situation, for sure. He'd rather have been starting, but it's nice that on nights he hasn't started, he's sitting there ready to hit."
Five days removed from a shellacking at the hands of the White Sox in which he allowed seven runs on 10 hits in just 2 1/3 innings, Paul Byrd rebounded nicely by scattering six hits over five frames of two-run ball.
"I was OK," Byrd said. "I got better as the game went on. I thought I had better stuff in Chicago, but it just didn't work out for me. Baseball's a weird game. It really is."
Byrd's efforts weren't rewarded with a victory, as the Orioles erased the Red Sox's 3-2 edge through five with a two-spot in the sixth against relievers Manny Delcarmen and Ramon Ramirez.
Jason Bay put Boston on top in the first, stroking a two-out, two-run single to left off Baltimore starter Jason Berken for his 99th and 100th RBIs of the season. The O's halved the deficit one inning later, when Matt Wieters scored on a bases-loaded double-play ball off the bat of Cesar Izturis.
After reaching on a fourth-inning error by first baseman Ty Wigginton and claiming second with a rare stolen base, Lowell came around on Jason Varitek's RBI double to left-center that armed the Red Sox with a 3-1 advantage.
Baltimore (56-83) responded with three unanswered runs over the next two frames to take a 4-3 lead into the bottom of the sixth.
"You have to remember that the other team is professional athletes, too," said Wagner, who struck out two in his lone inning of work. "They're not going to lie down just because we've got a good bullpen. They were turning it up a little bit, so we had to go out there and battle. We had some big hits when we needed them to give us a lead, and the bullpen held on and did what they were supposed to do."
Initially, that wasn't the case.
Relieving Byrd, Delcarmen retired just one of the five batters he faced to open the sixth before being pulled, with his bases-loaded walk to Brian Roberts tying the game at 3. Ramirez replaced Delcarmen and promptly surrendered an RBI single to Felix Pie, but he bounced back to fan Nolan Reimold and Nick Markakis.
"He really saved the game right there," Wagner said of Ramirez.
Boston plated the equalizer in the bottom of the frame, as Dustin Pedroia smashed a two-out comebacker off Matt Albers (2-5) that ricocheted off the pitcher and toward third base, allowing pinch-runner Joey Gathright to dash home from third.
Pedroia's knock and Wagner's 1-2-3 seventh set the stage for Martinez, who lined the first pitch he saw from Baez to left-center for a bases-clearing three-run double.
"Every time I go to the plate, I try to put together good at-bats and be a tough out," Martinez said. "That's it."
Mere weeks after trading in his Indians uniform for the heat of a playoff chase, it's safe to say Martinez could not have envisioned a better start with his new team.
"When you're in the middle of a race, it's always interesting," Martinez said. "Every game means something. You go to the ballpark every day and know that you're playing for something. That's a good feeling."
John Barone is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.