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 on Tuesday night.

Taking the mound 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 but lost for the first time in 24 professional appearances.

Nolan Arenado put St. Louis ahead with a fifth-inning home run on a first-pitch curveball, and Pittsburgh's Nick Gonzales 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. The crowd of 32,422 chanted "MVP" as Skenes emerged from the dugout.

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 Gonzales' 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.

"I felt good," Skenes said. "The complicated thing there is when I come out with no-hitters or whatever in the sixth or seventh inning, the reason I'm coming out in the sixth or seventh at 100 pitches is because I had some longer innings. Those were relatively quick. Low-stress, low-pressure innings. Kind of allowed me to keep going. It felt good."

Skenes allowed two runs and four hits in 8 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 innings in 2005.

Skenes had not pitched into the ninth inning since June 2 last year for LSU against Tulane. It was his first loss since May 25, 2023, when his LSU team fell to Arkansas in the SEC tournament.

"It felt like a playoff game with the atmosphere," St. Louis manager Oliver Marmol said. "Our guys competed hard against a very good pitcher. It was a fun game to be a part of."

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

"He threw the ball really well," Shelton said. "He threw two bad pitches in the whole game: the bad breaking ball to Arenado -- and, I mean, the pitch to Siani wasn't even a bad pitch, it was a good piece of hitting -- and then he threw an 0-2 pitch to Burleson and ended up right down the middle."

Arenado's 10th homer ended Skenes' streaks of nine hitless innings and 14 scoreless innings. Both are graduates of El Toro High School in Lake Forest, California.

"It's one pitch. Maybe it wasn't the right pitch to throw there," Skenes said. "I executed it well. He's a really good hitter. He's a [potential future] Hall of Famer. So, that stuff's going to happen. It's just about getting back and executing."

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 strikeout 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.

Information from The Associated Press was used in this report.