Branyan's two blasts -- estimated at 422 feet in the seventh inning against Brandon Webb and 456 feet in the ninth against Jorge Julio -- were awe inspiring, and his old teammate in the Cleveland system, Dave Roberts, was robbed of a four-hit night on a great play by shortstop Craig Counsell.
But in the end, the satisfaction was found in the other clubhouse.
With four hits, including his 20th homer, and four RBIs, Diamondbacks center fielder Eric Byrnes spelled doom for Woody Williams and the Padres.
It was an emotion-charged night for Webb, a Cy Young Award candidate who ran his record to 14-5 a day after learning that one of his best friends, Jon Hooker, and Hooker's new bride had perished in the plane crash that took 49 lives in Lexington, Ky.
A former college teammate of Webb and another Diamondbacks player, infielder Andy Green, Hooker had been married on Saturday night and was embarking on his honeymoon when the plane went down.
"I've never lost a real good friend like that," Williams said. "At his age, it seems like it's unfair.
"With everything Brandon Webb's going through, he did an outstanding job. He showed a lot of composure. I'm sure his teammates have a lot of respect for what he did."
Webb, who drove in the first two Arizona runs with a double in the second inning, went 7 1/3 innings, departing after Roberts' third hit, a triple, and a walk to Brian Giles. Todd Walker lined an RBI single against reliever Brandon Lyons, but Adrian Gonzalez hit into the fourth double play turned by Arizona, deepening the frustrations for the Padres.
In franchise history, the Padres are now 20-50 in Arizona, a .286 winning percentage. They've never won a season series in Phoenix.
Branyan, keeping in mind words of advice dispensed by Rettenmund in a pregame hitting session, stayed back and drove through the ball, making quite an impression on his new club.
The heralded Cleveland prospect from the '90s, now 30 and hoping to find a new home, sent a deep sacrifice fly to center in his first at-bat to deliver Gonzalez, who'd doubled leading off.
Webb escaped by getting Geoff Blum to hit into a fielder's choice and retiring Williams on a tapper to the mound.
"We had [Webb] on the ropes that inning and only mustered up one run," Padres manager Bruce Bochy said. "I thought that was the difference in the game. Woody's been so good, but he was off tonight. They put up crooked numbers, and we had a tough time getting a big inning."
Williams dropped to 7-5 with a five-inning outing, his briefest since July 27. He yielded 11 hits and five runs.
After singling in his first at-bat, Byrnes slammed a first-pitch solo homer in the third, and Johnny Estrada followed with another first-pitch blast, his 11th.
The Diamondbacks stretched the lead to 5-1 on Byrnes' RBI double in the fourth, and in the sixth, with Doug Brocail on the mound for the Friars, Byrnes smacked a one-out, two-run double to center after a pair of walks.
The last third of the game was Branyan's stage.
Facing Webb in the seventh after taking a third strike in the fourth inning, Branyan sent a tremendous drive into the seats in left-center. That one seemed impressive until he outdid himself in the ninth, launching a monstrous drive to right-center.
"Those are the best two balls I've hit in a while," Branyan said. "I was trying to get back to hitting the ball through the box, hands through the ball.
"Those are fundamental things I've been trying to work on all year, but Tampa Bay was tough. I couldn't find my swing at all. I had 160 some at-bats and couldn't get anything going. I don't know what the problem was. I was rolling over balls."
He batted .201 with 12 homers for the Devil Rays, playing mostly in the outfield, but he'll get a shot at third base in San Diego, where the door has been revolving since Vinny Castilla was released.
Branyan, aware of Rettenmund's reputation from his first term with the Padres and in Atlanta with the Braves, was delighted to hook up with the highly respected hitting coach.
"We went in the [batting] cage today and talked a lot," said Branyan, who joined the club on Saturday in Denver and made his first start on Sunday. "You hear about hitting coaches that players like, and he's one of them.
"In the short time I've been here, he's given me keys, building blocks. I tried to explain to him what I was doing, and he's asking me to simplify things. Some hitting coaches have that spark. Merv told me to keep it simple, see if I could carry it out the remainder of the season.
"I'm looking forward to getting back out there and getting better."