The Red Sox beat the Angels, 10-5, but on one unseasonably cool night in Boston, at least, the result of a contest between playoff contenders was secondary to an astonishing display of power.
Ortiz's grand slam made the difference. In the fifth, after five Red Sox players had reached base and two had scored, Big Papi ambled to the plate. The first pitch from Angels starter Jered Weaver, a fastball, zipped down the middle.
Ortiz rotated, his 230-pound body counterbalancing a swing of crushing force. The ball sailed high, and for a second, the only hang-up was whether or not it would stay within the imaginary vertical extension of Pesky's Pole in right field. It landed deep in the recesses of the bleachers. The stadium shook.
"That," manager Terry Francona said, "was well struck."
Then, the complexion of a game that began with five unanswered Angels runs off Curt Schilling changed dramatically. Weaver left two batters later, with one man down in the fifth and the Red Sox suddenly up, 6-5. He gave up six runs and six hits in that inning after holding the Red Sox scoreless through four frames.
"He was going right through us," Francona said.
Meanwhile, Vladimir Guerrero was doing all he could for the Angels. Before the game, the Los Angeles slugger gave a batting-practice performance reminiscent of his victorious romp through the 2007 Home Run Derby in San Francisco.
After it started, Guerrero picked up right where he left off, hammering a fifth-inning splitter that Schilling hung low, just off the plate, into the Green Monster seats.
"The only other guy that probably has ever done that to me," said Schilling, who gave up five earned runs and eight hits in six innings, "is [Alfonso] Soriano in the  World Series. I wanted to bounce it, so it wasn't a good pitch, in that sense.
"Fortunately, it ended up not being something that cost us the game."
Three games into the series, Guerrero is 7-for-14, with two doubles, a triple, a home run and five RBIs.
"That's the respect you need to have for Vlad because of what he can do," Francona said. "If he can reach it, he can hit it out of the ballpark."
Beyond Ortiz, there were less visible contributors. Mike Lowell credited Schilling, who earned his first win since his near no-hitter in Oakland on June 7, with sitting the Angels down in order in the sixth inning.
"Because they've got a lot of guys that can run," Lowell said. "They can put guys in motion. They can go first to third because they have such good team speed. So to not even let that be an issue, that's probably the biggest inning of the game right there."
Several players gave credit to Mike Timlin, who continued to get invaluable outs in the late-to-middle innings, complementing Schilling's six-inning start. Hideki Okajima and Jonathan Papelbon, meanwhile, rolled off perfect eighth and ninth innings, respectively.
Finally, there was Coco Crisp, who hit a pair of rockets that almost surely would have left smaller ballparks, including an off-the-wall double that he smoked four batters before Ortiz's slam.
In the seventh and eighth, Crisp recorded five straight outs in center, tracking balls with a dizzying combination of skill and speed.
"I thought Coco played an outstanding game," Francona said. "I mean, he was off almost ... on the pitch. He covered a lot of ground. And not only did he close in on balls, but he was moving when it was just going up.
"That was exciting to see."
And yet, fans will likely first remember the grand slam, Big Papi's emphatic return from a slight hiatus.
"We haven't seen that a lot this year," Kevin Youkilis said. "But you know it's there."
The last time Ortiz homered on consecutive days, as he did on Friday and Saturday, it was June 20 and the Red Sox were in Atlanta. The slugger has battled pain in his knee and shoulder all summer, and along with it, inconsistencies in his swing and stingy opposing pitching. With the bases loaded, this time, Ortiz was ready for a fastball.
"I kind of put it in my mind [that], OK, he's going to try to throw a pitch for a strike to get ahead," Ortiz said, "and I'm going to try to hit it far."
"I don't know, man," Ortiz said. "I don't measure my homers. But that was a pretty good one."
Alex McPhillips is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.