ST. LOUIS (Interstat) — Jackson Merrill hit a two-run homer in the ninth inning and the San Diego Padres broke open a close game with three runs in the final frame to beat the St. Louis Cardinals 6-1 Wednesday afternoon at Busch Stadium III.

Attendance was 29,859, and the game lasted 2 hours, 52 minutes.

The Padres avoided a three-game sweep after losing the first two games of the series by scores of 3-2 and 3-0. San Diego improved to 38-35, while St. Louis dropped to 40-32.

Griffin Canning earned his first win of the season, allowing one run on four hits over 4 1/3 innings. He struck out two and walked two. Canning entered the game with an 0-5 record and had been tagged for seven earned runs in his previous start at Baltimore on June 12. He kept the Cardinals off balance for much of his outing, departing after throwing 63 pitches.

Kyle Leahy took the loss for St. Louis, falling to 5-4. He pitched six innings, giving up three runs on seven hits while striking out seven and walking one. Leahy was efficient but lacked offensive support.

San Diego took a 1-0 lead in the first inning. Samad Taylor walked, advanced to third on a single by Merrill and scored on a sacrifice fly by Manny Machado.

The Padres added a run in the fourth. Machado led off with a double and scored on a single by Xander Bogaerts. San Diego made it 3-0 in the fifth when Will Wagner singled, moved up on a groundout and crossed the plate on a double by Fernando Tatis Jr.

St. Louis’ only run came in the bottom of the fifth. Blaze Jordan walked and Nathan Church singled. After a groundout moved the runners to second and third, Iván Herrera’s fielder’s choice cut down Jordan at the plate. Alec Burleson then singled to left, scoring Church and cutting the deficit to 3-1.

The Padres threatened in the eighth, loading the bases with two outs, but Ty France lined out to left field to end the inning.

San Diego broke the game open in the ninth against the St. Louis bullpen. Sung-Mun Song led off with a single and advanced to second on a groundout. Tatis followed with a sharp single to right field, scoring Song. Tatis was thrown out trying to advance to second on the play. Samad Taylor singled, and then Merrill crushed an 0-1 pitch over the right-field wall for his eighth home run of the season, scoring Taylor and giving San Diego a 6-1 lead.

Merrill finished 3 for 5 with two RBIs. Tatis also went 3 for 5 and drove in two runs.

The Cardinals had chances but hit into two double plays and left five runners on base. San Diego hit into two double plays as well but outhit St. Louis 14-6.

Kyle Hart relieved Canning and pitched 1 2/3 scoreless innings, allowing no hits with one strikeout. Jason Adam, Bradgley Rodriguez and Adrian Morejon each threw a scoreless inning to close out the game.

St. Louis had the potential tying run at the plate in the fifth after scoring its only run, but Jordan Walker grounded into a forceout to end the inning. The Cardinals also failed to capitalize on a leadoff walk in the sixth and a hit batter in the eighth.

Lars Nootbaar, Masyn Winn and Iván Herrera each had one hit for St. Louis. Burleson drove in the Cardinals’ lone run with his single.

The series was the third meeting between the teams this season. St. Louis had won four of the previous six head-to-head games, including a four-game split in San Diego in early May.

San Diego travels to Texas for a three-game series against the Rangers starting Friday. St. Louis heads to Kansas City for a three-game set beginning Thursday.

Interstat’s game simulator had projected a final score of St. Louis 7, San Diego 5. Interstat’s ELO system gave St. Louis a 51.30 percent probability to win. San Diego was installed as a pregame favorite with a spread of minus 1.5. The total score of 7 went over the over/under line of 10.