Pittsburgh Pirates starting pitcher Paul Skenes delivers during the second inning of a baseball game against the St. Louis Cardinals, Tuesday, July 23, 2024, in Pittsburgh. (AP Photo/Matt Freed)

PITTSBURGH — Rookie Paul Skenes lost for the first time in 12 career major league starts, giving up Alec Burleson's tiebreaking single in the ninth inning that lifted the St. Louis Cardinals over the Pittsburgh Pirates 2-1 Tuesday night.

Pitching for the first time since starting for the National League in last week's All-Star Game, the 22-year-old right-hander pitched past the seventh inning for the first time in the major leagues.

Nolan Arenado put St. Louis ahead with a fifth-inning home run on a first-pitch curveball, and Nick Gonzalez tied the score with an RBI single in the eighth off JoJo Romero.

Skenes (6-1) threw 91 pitches through eight innings, and Pirates manager Derek Shelton allowed him to remain on the mound for the ninth.

Michael Siani doubled down the left-field line on a 1-2 fastball leading off — he was called out at second by umpire Sean Barber, but a video review showed Siani's left hand slapped the base before Gonzalez's tag following the throw from left fielder Bryan Reynolds.

Siani took third on Masyn Wynn’s groundout and scored when Burleson lined an 0-2 fastball into right on Skenes' 104th and final pitch.

Skenes allowed two runs and four hits in 8 1/3 innings with eight strikeouts and no walks as his ERA rose to 1.93 from 1.90. He had seven or more strikeouts for his ninth straight start, extending a team record. No Pirates rookie had pitched as long as Skenes since Zach Duke threw 8 1/3 innings in 2005.

Skenes threw 78 pitches for strikes and reached 100 mph with three pitches, raising his total to 78.

Arenado's 10th homer ended Skenes' streaks of nine hitless innings and 14 scoreless innings.

Ryan Fernandez (1-2) induced an inning-ending double play in the eighth from Ke’Bryan Hayes, his only batter.

Ryan Helsley struck out three straight batters on 13 pitches for his 33rd save in 35 chances.

Lance Lynn allowed four hits and three walks in five innings. He struck out two, including Jared Triolo to end the fourth inning for the 2,000th of his 13-year big league career. Catcher Willson Contreras threw the ball into the stands but was able to retrieve it by giving the fan a bat.

Jack Suwinski had two hits for the Pirates, who had won seven of their previous eight games.

St. Louis signed their top pick in the amateur draft and seventh overall selection, West Virginia infielder JJ Wetherholt, for a $6.9 million bonus, just above the $6,823,700 slot value. He was the Big 12 player of the year in 2023, when he led the NCAA in hitting. Wetherholt played at Mars High School.

Pirates: LHP Bailey Falter (left triceps tendinitis) is scheduled to make his first rehab start on Wednesday night with Triple-A Indianapolis. … RHP Jared Jones (right lat strain) is on track to throw a bullpen this weekend for the first time since being injured on July 3.

The three-game series concludes Wednesday with the Pirates starting LHP Martín Pérez (1-5, 5.61 ERA), who will be looking for his first win since April 4, a span of 13 starts.