CINCINNATI (AP) — It’s hard to rattle Johnny Cueto these days.

The right-hander, who was prone to meltdowns as a rookie, extended his scoreless streak to 15 innings Friday night before giving up his only run, and the Cincinnati Reds won their second in a row with a depleted lineup, 6-4 over the St. Louis Cardinals.

Cueto (3-1) had his way with a team that hit him hard during his rookie season. He limited the Cardinals to a run and five hits in seven innings Friday, leaving with a 6-1 lead. It was the latest measure of how far he’s come.

‘‘He’s full of confidence,’’ manager Dusty Baker said.

The 23-year-old pitcher appears to be maturing at the start of his second season. Last year, he would get rattled by a mistake, allowing it to multiply into a big inning. In his last five starts, Cueto has allowed only three earned runs, refusing to get on the defensive when something goes wrong.

‘‘I’m trying to be more aggressive,’’ Cueto said in Spanish, with teammate Ramon Hernandez translating. ‘‘Last year, I think I was moving my glove and tipping my pitches, so I’m not doing that this year. I’m just trying to be more aggressive and make them put the ball in play.’’

David Weathers gave up three runs in the eighth, including Tyler Greene’s first career homer — the first runs off the reliever in 11 appearances this season. Francisco Cordero pitched the ninth, remaining perfect in his nine save chances with the help of his catcher.

Joe Thurston drew a leadoff walk. With pinch-hitter Jason LaRue at the plate, Thurston took off and was caught trying to steal by catcher Ryan Hanigan.

‘‘He got a bad jump,’’ manager Tony La Russa said. ‘‘I put the (steal) sign on, right or wrong. That’s how it turned out.’’