ST. LOUIS (Interstat) — Tyler Locklear homered and drove in three runs, and the Arizona Diamondbacks broke open a tight game with a five-run eighth inning to beat the St. Louis Cardinals 10-6 on Thursday night at Busch Stadium III.

Locklear, making his mark in his first full season with Arizona, went 3 for 5 with a home run and three RBI. He had been 1 for 2 with an RBI in Tuesday’s win over Oakland, 0 for 3 in a loss to the Athletics on Monday and 1 for 3 with an RBI in Sunday’s extra-inning win over these same Cardinals.

The Diamondbacks improved to 54-49, while the Cardinals fell to 52-50.

Arizona starter Brandon Pfaadt earned the win, his fifth against one loss this season. Pfaadt worked six innings, allowing seven hits and two earned runs while striking out one. The Cardinals’ Michael McGreevy took the loss, falling to 4-8 after giving up seven hits and four earned runs in 6 1/3 innings with three strikeouts.

The Cardinals struck first in the bottom of the first inning. JJ Wetherholt singled, then Jordan Walker doubled him home for a 1-0 lead. Alec Burleson singled, and Lars Nootbaar followed with a single to score Walker, making it 2-0. Pfaadt escaped further damage by striking out Nathan Church and getting a flyout from Blaze Jordan.

Arizona’s bats were quiet early against McGreevy. Through three innings, the Diamondbacks managed only a double from Locklear in the third, but he was stranded.

The Diamondbacks tied the game in the fourth. Max Kepler walked, and Adrian Del Castillo doubled to put runners at second and third. Tim Tawa’s sacrifice fly to center scored Kepler, cutting the lead to 2-1. After Ildemaro Vargas grounded out, Locklear launched a line-drive home run to left field, scoring Del Castillo and giving Arizona a 3-2 lead.

Arizona added a run in the fifth. Corbin Carroll tripled to center, his 12th of the season, and scored on Gabriel Moreno’s sacrifice fly to left, making it 4-2.

Pfaadt held the Cardinals in check through the middle innings. St. Louis put a runner on second in the third but could not score. In the fourth, Jimmy Crooks singled but was erased on a double play. The Cardinals managed only a single in the sixth and a single in the seventh, but Pfaadt worked around both threats.

The game turned decisively in the eighth inning. Moreno led off with a double off McGreevy. Kepler grounded out, but Del Castillo singled to left, scoring Moreno to push the lead to 5-2. Tim Tawa walked, and Vargas singled to load the bases. Locklear then lined a single to center, scoring Del Castillo to make it 6-2. Nolan Arenado, pinch-hitting, singled to right, scoring Tawa for a 7-2 lead. Carroll’s sacrifice fly to left scored Vargas, making it 8-2. Geraldo Perdomo walked to load the bases again. Moreno then singled to right, scoring Locklear for a 9-2 advantage. Kepler popped out to end the inning, but the damage was done.

Arizona’s five-run eighth was the deciding stretch. The inning featured four singles, a double, a walk, a sacrifice fly and a pinch-hit single from Arenado, who later added an additional hit in the ninth.

Arizona added an insurance run in the ninth. Del Castillo singled to right, and after a strikeout, Vargas singled. Locklear struck out, but Arenado lined a single to left, scoring Del Castillo to make it 10-2.

The Cardinals mounted a rally in their final at-bat. Nathan Church singled to lead off, but Blaze Jordan and Pedro Pagés both popped out. Wetherholt singled, and Bryan Torres lined a single to right, scoring Church and Wetherholt to cut the lead to 10-4. Alec Burleson doubled, and Nootbaar singled to center, scoring Torres and Burleson to make it 10-6. Masyn Winn grounded out to second to end the game.

Arizona’s bullpen held on. Taylor Clarke pitched a scoreless eighth inning, allowing no hits. Brandyn Garcia worked the ninth, allowing one hit and one earned run while striking out one.

For Arizona, Gabriel Moreno went 3 for 4 with two RBI. Adrian Del Castillo went 3 for 5 with an RBI. Arenado finished 2 for 2 with two RBI as a pinch-hitter and then designated hitter. Ildemaro Vargas added three hits.

For St. Louis, Alec Burleson went 3 for 5 with a double. Lars Nootbaar went 2 for 5 with three RBI. Jordan Walker doubled and drove in a run.

The Diamondbacks rapped out 16 hits, while the Cardinals collected 13. Arizona made three sacrifice flies and grounded into two double plays. Arizona pitchers combined for seven strikes, 62 balls and seven balls in play. St. Louis pitchers combined for 12 strikes, 40 balls and 12 balls in play.

The attendance was 32,381. The game lasted 2 hours, 54 minutes.

Arizona’s previous results include a 15-5 win over on Wednesday, a 6-5 win in 10 innings Tuesday and a 2-5 loss Monday. The Diamondbacks took two of three from St. Louis in a series at home from July 17-19, winning 8-7 in 10 innings Sunday and 5-3 Saturday but losing 5-4 Friday.

St. Louis’ recent results include a 1-0 win at the Los Angeles Angels on Wednesday, a 1-5 loss Tuesday and a 2-3 loss Monday. The Cardinals had split the previous six meetings with Arizona, with each team winning three.

The Interstat game simulator projected a final score of Arizona 6, St. Louis 4. Interstat’s ELO system gave St. Louis a 50.90 percent probability to win. The Cardinals were installed as a pregame favorite with a spread of minus-1.5. The total score of 16 went under the over/under line of 8.5.