Seth Smith hit a walk-off home run to cap an amazing rally as the Colorado Rockies overcame their largest ninth-inning deficit in franchise history to shock the St. Louis Cardinals 12-9 on Tuesday night.

Entering the ninth trailing 9-3, Miguel Olivo led off the inning with a single off Dennis Reyes. Reyes recorded one more out before giving up another single to Melvin Mora and walking Clint Barmes, allowing Olivo to score on a wild pitch.

St. Louis then brought in closer Ryan Franklin, who completely fell apart. Chris Iannetta immediately hit a three-run homer off Franklin to make it 9-7 and then Dexter Fowler followed with a double.

Pinch-hitter Brad Hawpe grounded out to shortstop and then Carlos Gonzalez hit a two-out single to make it 9-8 and bring the tying run to the plate in the form of Jason Giambi.

Giambi delivered a single which was bobbled by right fielder Randy Winn and allowed Gonzalez to score all the way from first and tie the game.

But Colorado wasn’t finished; Olivo singled for the second time in the inning and Smith then capped the rally with a no-doubter to right field.

St. Louis gave up nine runs and eight hits in that final frame. Franklin (3-1) took the loss, giving up six runs on six hits while getting just one out.

Manny Corpas (3-5) earned the win by pitching two perfect innings.

The bullpen implosion spoiled a solid start by St. Louis pitcher Blake Hawksworth. Hawksworth went five innings in his fourth start of the season, allowing two runs on eight hits. He walked four and struck out five.

The Rockies’ comeback also let Colorado starter Jeff Francis off the hook. He got roughed up for the second straight start, allowing five runs on six hits in just four innings after giving up eight runs his last outing. The 29-year-old lefty gave up one earned run in his first two starts combined, but has struggled since and saw his ERA rise to 5.12.

Felipe Lopez started the scoring for St. Louis with a two-run homer in the third inning. Pujols followed two batters later with an RBI double to make it 3-0. Gonzalez, who went 4-for-6 with three RBIs, homered in the bottom of the frame to make it 3-2, but then the Cards put their foot on the gas.

Miles hit a sacrifice fly in the fourth and Lopez followed with an RBI single. Yadier Molina tacked on another run in the fifth with a single and Matt Holliday hit a three-run shot in the sixth to extend the lead to 9-2.

Iannetta made the score 9-3 in the seventh with an RBI groundout before Colorado made its historic comeback.