Willson Contreras’ walk-off RBI single in the 10th inning lifted the St. Louis Cardinals past the visiting Kansas City Royals 6-5 on Thursday in Game 1 of a split doubleheader.

Contreras, playing in his 1,000th game, also hit a double and scored a run. Ivan Herrera added a two-run homer for the Cardinals.

Cardinals starter Miles Mikolas allowed three runs on eight hits in six innings. He walked one and struck out two. Reliever JoJo Romero (2-3) claimed the victory after allowing an unearned run in the top of the 10th.

Royals starter Noah Cameron blanked the Cardinals for six innings on two hits while striking out three and walking two. Reliever Carlos Estevez (2-1) took the loss.

Vinny Pasquantino drove in two runs and Jonathan India had a homer and two RBIs for the Royals. Jac Caglianone hit a run-scoring double for his first major league hit and RBI.

India homered to lead off the game, then Kansas City increased its lead to 2-0 in the fourth on doubles by Salvador Perez and Caglianone.

Royals made it 3-0 in the fifth. Bobby Witt Jr. hit a one-out single, stole second, moved to third on a flyout and scored on Pasquantino’s single.

The Cardinals cut their deficit to 3-2 in the seventh. Contreras greeted reliever John Schreiber with a double, took third on Herrera’s single and scored on Nolan Arenado’s fielder’s choice. Alec Burleson hit a single, Ryan Vilade reached on an error, pinch-hitter Yohel Pozo followed with a sacrifice fly.

St. Louis moved ahead 4-3 in the eighth inning when Daniel Lynch IV hit Brendan Donovan with a pitch and surrendered Herrera’s two-run homer.

The Royals tied the game against closer Ryan Helsley in the ninth on singles by Michael Massey and Kyle Isbel and India’s sacrifice fly.

Pasquantino’s RBI single put the Royals up 5-4 in the 10th inning, but the Cardinals answered with Masyn Winn’s run-scoring groundout and Contreras’ walk-off single to left with one out.