As crunch time nears, the Rockies are crumbling.

San Diego beat them 5-3 at Petco Park on Wednesday night to complete a three-game sweep, dropping the Rockies’ record to 20-23. With just 17 games left in the 60-game season, there is little remaining margin for error if Colorado wants to be one of eight National League teams to qualify for the expanded playoffs. They currently sit as the NL’s ninth-place team.

Wednesday night’s game was a sequel to Tuesday’s night’s loss, just not quite as ugly.

The Rockies got off to an encouraging start, just as they did Tuesday night in a 15-4 loss to the Padres. In the first, Trevor Story waited on Zach Davies’ changeup and drove it 426 feet to left-center for a solo homer. Story’s 10th homer of the season came off the bat at 104 mph, remarkable, considering that Davies’ changeup arrived at just 79 mph.

The lead didn’t last long.

Colorado starter Antonio Senzatela, a bit off with his command, gave up three hits in the first, including a double to Manny Machado followed by Mitch Moreland’s two-run homer.

The Rockies retook the lead, 3-2, in the sixth on Nolan Arenado’s double followed by Matt Kemp’s two-run homer. Kemp’s fifth homer of the season gave him 20 RBIs, 11 of which have come against San Diego.

The lead didn’t last long. Sensing a pattern here?

Senzatela, who controlled the Padres in innings two through five, got lit up in the sixth. A leadoff walk by Mitch Moreland, an RBI triple by Rockies killer Wil Myers and Jake Cronenworth’s run-scoring single put the Padres ahead, 4-3.

Senzatela was charged with four runs on six hits over six innings. He struck out two and walked four.

Reliever Tyler Kinley limited the damage, striking out Abraham Almonte and getting Jurickson Profar to bounce into a double play. Kinley then set the Padres down in order in the seventh to keep Colorado in the game.

San Diego sealed the deal in the eighth off right-hander Mychal Givens. Myers ripped a one-out double to left and scored on Austin Nola’s single. In his career vs. Colorado, Myers is batting .347 (119-for-343) with 30 doubles, five triples and 23 home runs.

The Rockies had their chances to rally, but they went 1-for-8 with runners in scoring position.

In the seventh, Elias Diaz hit a one-out single and took second when Myers bobbled the ball in right field. But Diaz was stranded when Raimel Tapia popped out to left and Story struck out.

In the eighth, Colorado put men on first and second against Drew Pomeranz with an infield single by Charlie Blackmon and an opposite-field single by Kevin Pillar. But they were marooned when Pomeranz struck out Kemp with a high fastball and got Josh Fuentes to chop the ball back to the mound.

The Rockies are off Thursday before hosting the Los Angeles Angels on Friday to begin a crucial nine-game homestand.