The plan changed in the seventh inning, with the bases loaded and the Phillies trailing by three runs. Arizona brought in right-hander Brandon Medders, and Howard greeted him with a pinch-hit grand slam to lead the Phillies to a 9-3 victory on Wednesday night.
Howard, who entered hitting .198, hit reliever Medders' (1-1) first pitch 371 feet into the right field seats. It was the fourth grand slam of Howard's career and his fourth pinch-hit homer.
"It was set up perfect, really, because once they brought the right-hander in he had to face a hitter," Manuel said. "I mean, that's exactly the matchup we wanted."
With the victory, the Phillies averted a three-game sweep by the Diamondbacks and wrapped up a 4-6 road trip to Atlanta, San Francisco and Arizona.
"It's huge," Howard said. "We've been kind of up and down, trying to get a good end on this road trip. It helps us get out of here on a good note and get something started."
The Phillies hope the homer will signal an end to Howard's season-long slump.
"Ryan's going to be fine," Manuel said. "Ryan's special. He's been kind of fighting himself. This guy wants to do so good. When it's all said and done, he's going to have a tremendous year for us."
Howard's shot gave Jamie Moyer (4-2) the victory in the matchup of the oldest lefties in history -- the 44-year-old Moyer against Johnson, 43.
At a combined 88 years and 48 days, Johnson and Moyer broke the record set April 24 when Johnson faced San Diego's David Wells. Johnson and Wells were a combined 87 years and 300 days.
Striking out nine, including the first six men he faced, Johnson looked like the Big Unit who won five Cy Young awards. Johnson, who underwent back surgery last October, is still looking for his first victory in his return to Arizona after two frustrating seasons with the New York Yankees.
"I may have been the old Randy for six innings," Johnson said. "Then I just got old."
Still, Arizona manager Bob Melvin liked what he saw from Johnson.
"Great slider, good velocity on his fastball, had some edge, the whole bit," Melvin said. "He just pitched very well."
While Johnson was mowing down the Phillies, Moyer didn't let the Diamondbacks blow the game open. Pitching with his trademark efficiency, he allowed three runs and six hits in six-plus innings. He walked one and struck out four.
"I've seen Randy pitch my fair share of times," Moyer said. "You respect the pitcher that he is and the competitor that he is. I was able to keep it somewhat close."
Johnson outpitched his elder until the seventh, when he gave up a single to Aaron Roward, hit Chase Utley and walked Pat Burrell to load the bases with no outs. That's when Melvin summoned Medders, whose first delivery ended up in the seats.
It was the sixth homer for Howard, who hit a franchise-record 58 homers a year ago.
"I was just coming in trying to look for something good in the zone, just trying to knock in some runs," Howard said. "It wound up going over the fence."
Medders said he threw Howard an inside fastball, as he was instructed to do by his coaches.
"I got it in," Medders said. "That's where they wanted it. Good piece of hitting. I tip my hat."
Brett Myers pitched the final two innings for his third save in three chances.
Leading 6-3, the Phillies scored three runs in the ninth -- capped by Shane Victorino's two-run homer.
- Johnson came within two of the modern record for strikeouts to start a game. Pitching for Houston, Jim Deshaies fanned the first eight Dodgers he faced on Sept. 23, 1986, in Houston.
- Johnson's streak came two weeks after San Diego's Jake Peavy fanned nine straight Diamondbacks in a 3-2 loss to Arizona April 25 in Chase Field. Peavy came within one strike of former Met Tom Seaver's major league record for consecutive strikeouts, set on April 22, 1970, against San Diego.
- Johnson and Moyer met for the first time since Sept. 21, 1989, when Johnson pitched for Seattle and Moyer Texas. The span of 17 years, 230 days is the longest period between starters for opposing pitchers in history. Asked if he remembered that game, Moyer replied, "No, do you?"