He got a big ovation from the crowd when he was introduced as a pinch-hitter in the sixth inning, singled off Josh Johnson to load the bases, then came sliding home on Jerry Hairston Jr.'s two-run double that helped the NL West leaders beat the Florida Marlins 5-4 and avoid a three-game sweep.
"I'll never forget, I slid across home plate and I had guys standing right there pumping their fists, fired up," said Ludwick, acquired Saturday from St. Louis in a three-team deal that also included Cleveland.
"There was a lot of excitement," the former All-Star said. "It was a lot of fun to see these guys today, the way they acted on the bench, on the field and the way they greeted me in the clubhouse."
The Padres kept San Francisco from creeping any closer in the division race. San Diego entered the day with a 1 1/2-game lead over the Giants, who played the Los Angeles Dodgers on Sunday night.
"We're a confident group," said Hairston, whose double capped a three-run rally in the sixth. "The last couple of days have been a little crazy, a lot of uneasiness, a lot of guys don't know if they're going to get traded or maybe sent down. But with the additions we have, no question they will help our ballclub.
"We have our team now and hopefully we'll make a really good run."
San Diego right-hander Jon Garland (10-7) outpitched Johnson (10-4), allowing three runs and five hits in six innings with six strikeouts and three walks. Johnson gave up seven hits and a season-high five runs in 5 2/3 innings. He struck out five and walked four.
By comparison, Johnson gave up a total of five earned runs in five starts in June, and another five earned runs in five starts in July. His major league-leading ERA rose from 1.72 to 1.96. It was the first time in 20 starts he didn't pitch at least six innings.
"I just didn't make my pitches," he said. "My slider was more middle than toward the outside corner. When you have that, you have to make a perfect pitch every time."
Marlins manager Edwin Rodriguez said the Padres "made adjustments on him. They beat him, they beat us, they beat our best pitcher. He didn't have his best stuff today. But I still think he pitched well."
Trailing 3-2, the Padres loaded the bases with one out in the sixth on a single by Yorvit Torrealba, a walk to Will Venable and, after Scott Hairston popped up to Johnson while bunting, a single to left by Ludwick.
Chris Denorfia hit a sacrifice fly to tie the game and Hairston put the Padres ahead with his double over the head of Morrison, the left fielder.
Ludwick recently spent time on the disabled list with a calf injury, but he showed no ill effects as he raced from first to home. The relay throw got to catcher Ronny Paulino just before Ludwick got to the plate, but by the time Paulino turned to apply the tag, Ludwick came sliding in and touched the plate with his left hand.
"It's always good, with a pitcher like that, the year he's having, for the guys to come up big and get those runs," Garland said. "It's huge. You avoid a sweep, you go into L.A. with a little bit of momentum and hopefully we can keep it going."
The Padres open a four-game series Monday night at Los Angeles.
Torrealba had three hits and extended his hitting streak to 14 games. He hit a two-run double in the first, but the lead didn't last long. Paulino's two-out single in the second brought in Cody Ross, who singled and went to third on Garland's error on a pickoff attempt.
Hanley Ramirez tied it with a leadoff homer in the third, the Marlins' fifth homer this series and 13th on their seven-game trip. Ramirez's shot, which reached the second deck in left, was his 14th.
The Marlins went ahead 3-2 on Wes Helms' two-out single in the sixth.
Miguel Tejada is 1 for 10 with two walks and a run scored in three games with the Padres. ... It was the second straight start Johnson allowed three earned runs or more. He had not allowed more than two earned runs in any of his previous 13 starts. ... Left-handed reliever Will Ohman made his Marlins debut with one-third of an inning in relief of Johnson. Ohman reported a day after being obtained from Baltimore in exchange for RHP Rick VandenHurk.