PHOENIX (Interstat) — The St. Louis Cardinals and Arizona Diamondbacks close out their three-game series Sunday evening at Chase Field in a pivotal National League matchup.

St. Louis (51-46) holds a one-game lead over Arizona (50-48) in the standings, but the Diamondbacks have claimed two of the first three meetings this weekend, including a 5-3 victory Saturday. Arizona won Saturday behind a strong start from right-hander Brandon Pfaadt, who has emerged as a key figure in the Diamondbacks’ rotation.

Pfaadt, the player to watch for Arizona, has won four consecutive decisions. Over his past four starts (Interstat) — all wins (Interstat) — he has allowed just five earned runs across 21 innings, striking out 13. His most recent outing came Saturday against St. Louis, when he worked 5 1/3 innings, allowed two earned runs on six hits and struck out three. Pfaadt also tossed five scoreless innings July 6 at San Diego and has not allowed more than two earned runs in any start since June 24.

For St. Louis, reliever Gordon Graceffo has been a steady presence out of the bullpen. The right-hander has not allowed an earned run in seven consecutive appearances dating to July 1. In that span, covering 7 2/3 innings, Graceffo has surrendered just three hits, walked none and struck out 10. He worked a scoreless inning Saturday, striking out two. Over 11 appearances this season against the Diamondbacks, Graceffo has a 1.69 ERA.

The two teams have split the season series 3-3, with Arizona winning two of three at home and St. Louis taking two of three in their earlier meeting at Busch Stadium in June.

According to Interstat’s game simulator, Arizona is projected to win 6-4. The Cardinals enter as a -1.5 favorite on the run line, and the over/under is set at 8.5 runs.

St. Louis will travel to Los Angeles to face the Angels on Monday, while Arizona returns home to host the Athletics.

First pitch is scheduled for 6:40 p.m. MST.