"It feels cool," said Gonzalez, who also had a single in the game and is batting .276 with 98 RBIs this year. "Thirty-nine and 40 is basically the same thing, but it's a cool accomplishment. It's like hitting .299 instead of .300. That would be the same thing."
Nate Colbert, one the stars of the club's first decade, had 38 homers in 1970 and '72 before the low inner wall was installed at what was then called San Diego Stadium. The fact is that Gonzalez is the first Padres player to reach 40 since the team moved into spacious PETCO Park in 2004, and only 12 of his homers this season have come at home.
"I definitely do think it's a harder thing to do at PETCO," Gonzalez said. "PETCO is a pitchers' park. I've been able to get most of my homers on the road, because it's so tough to hit them at PETCO. That's part of the game."
Asked if he had had any discussions with new Padres chief executive Jeff Moorad about the dimensions of PETCO, Gonzalez simply said, "no."
The Padres have hit 137 homers this season, including 57 at home.
"It's a great accomplishment," San Diego manager Bud Black said. "It just shows where he is in his career. He's continued to improve on his game. He's one of the premier power hitters in the National League."
The Gonzalez blast was offset by Chad Tracy's second homer in as many games and eighth of the season. Tracy, who drilled a pinch-hit, seventh-inning grand slam to win Saturday night's game, 8-5, started at first base on Sunday.
Tracy had a single, double and homer off Padres starter Edward Mujica. His homer came with one out in the sixth, an inning during which the D-backs scored three times. Stephen Drew knocked in a pair of runs in the inning with a double, giving the D-backs a lead they never surrendered.
Tracy's homer was disputed, though, and for the third time in the past five games played here, umpires went to instant replay to determine its legitimacy.
Tony Gwynn, playing center field for the Padres, went above the fence in front of the right-center-field pool area and said his glove deflected off a female fan's chest. The question was whether the woman had reached below the top of the wall. After review, though, crew chief Rick Reed upheld the call.
"If she wasn't there, there's no question in mind that that ball was playable," said Gwynn, who returned to give the woman the ball after it deflected on to the field. "I wanted to get her take on it. She thought she was hanging over the wall, too. She said she was sorry. At the end of the day, she was just trying to protect herself, I think."
The Padres finished their 10-game road trip through Pittsburgh, Colorado and Arizona with a 6-4 record. For the season, their final road record was 33-48.
They head home for their final five games -- a two-game set against the Dodgers, which opens on Tuesday night, and a three-game weekend season closer vs. the Giants that begins on Friday night.
"I'm pleased with the way we played on the 10-game road trip," Black said. "I think that's a great sign, especially going through three time zones. We won the last three in Pittsburgh. We went to Colorado to a venue where they're hungry for a playoff spot and won two out of three. And the games here were close."