The Rockies, who not long ago had visions of making a run toward .500 as Tuesday’s trade deadline approached, are instead headed toward Antarctica.

In other words, they’re going south.

Monday night at San Diego’s Petco Park, they were one and done.

The Padres ambushed the Rockies and starter Antonio Senzatela for three runs in the first inning. “Senza” buckled down after that and pitched a fine game.

It didn’t matter. The Rockies’ road offense was mostly a no-show — again — and the Padres rode their first inning to a 4-1 victory.

Colorado hit no home runs, which is not a surprise. They have hit only 29 homers on the road, the fewest in the majors.

” ‘Senza put up five zeroes and kept us in the game, we just fell short with the offense,” manager Bud Black told reporters in San Diego.

The Rockies are 3-8 since the All-Star break and with a 46-58 record fell 12 games under .500, matching their low-water mark of the season. The Padres (58-46) remain in the thick of the National League wild-card race.

San Diego left fielder Jurickson Profar led off the first with a homer to right-center on Senzatela’s second pitch of the game, a 1-0 fastball.

Then Manny Machado ripped a double to left, Jake Cronenworth walked and Luke Voit’s groundout to second baseman Brendan Rodgers advanced Machado to third. Rodgers had a chance for a possible double play — or at the very least a chance to get the runner at second — but Rodgers bobbled the ball and had to settle for the out at first.

It was a costly mistake because Wil Myer’s groundout to shortstop Jose Iglesias scored Machado and Nomar Mazara’s bizarre, broken-bat, infield hit ricocheted off the first-base bag, scoring Cronenworth.

Senzatela, who began mixing his pitches after his rocky first frame, cruised for his next five innings and finished the night allowing just five hits while striking out five. He did walk three, snapping a streak of having walked two or fewer batters in 28 consecutive starts dating back to July 1 of last season, the longest streak in franchise history.

Black, who had a teaching moment with Senzatela in the dugout after the first inning, said he didn’t tell the right-hander anything specific.

“Just some general principles that I wanted him to hear from me,” Black told reporters. “And good for him, that he applied them. He was frustrated, obviously, with the first three at-bats.”

The Padres tacked on a bonus run in the eighth on Trent Grisham’s one-out homer off of reliever Carlos Estevez. The right-hander threw a 3-2, 98.5 mph fastball to Grisham — a good pitch — but Grisham powered it out to left-center for his 11th homer of the season.

Padres right-hander Mike Clevinger dominated the Rockies for seven innings. He allowed five hits, fanned six and walked none.

Colorado’s lone run arrived in the sixth. Jose Iglesias led off with a double, moved to third on C.J. Cron’s single to right, and scored on Rodgers’ sacrifice fly to deep right field.

Tuesday, the Rockies and Padres play a scheduled doubleheader, part of a five-game series over four days at Petco.

On Deck

Rockies RHP José Ureña (1-3, 4.67 ERA) and RHP Ryan Feltner (1-3, 5.59) at Padres TBA
Doubleheader, 2:10 p.m. and 8:10 p.m. Tuesday, Petco Park
TV: ATTRM
Radio: 850 AM/94.1 FM

Rockies manager Bud Black said Monday that he hadn’t decided yet whether Urena or Feltner will start in Game 1 of Tuesday’s doubleheader. Urena, so good in his first three starts with the Rockies, got shelled by the Dodgers on Thursday at Coors Field. With his command AWOL, he allowed 10 runs (seven earned) on eight hits and three walks while striking out two over three-plus innings. He gave up multiple runs in each of the first two innings and then failed to record an out and put four runners aboard in the fourth before Austin Gomber was brought in to relieve him.

Feltner has been up and down between Triple-A and the big leagues all season. He pitched 3 1/3 scoreless innings of relief against the Dodgers on Friday, giving up three hits and two walks while fanning two. The rookie right-hander is 1-3 with a 6.15 ERA in seven starts this season.

Trending: Second baseman Brendan Rodgers entered Monday night’s game leading major league second basemen with 100 hits and led all National League second basemen in RBIs (49) and extra-base hits (34). Rodgers had hit safely in 14 of his last 16 games, batting .385 (25-for-65) over that span.

At issue: The Rockies’ 72 errors were the second-most in the majors behind the Pirates, entering Monday night’s game. Colorado was 30-28 this season when committing no errors, 15-34 when making at least one error and 3-16 when committing two or more errors.

Pitching probables

Wednesday: Rockies RHP Chad Kuhl (6-6, 4.59) at Padres TBA, 7:40 p.m., ATTRM
Thursday: Rockies LHP Kyle Freeland (6-7, 4.63) at Padres TBA, 2:10 p.m., ATTRM