The left-hander allowed one unearned run on five singles and struck out seven at Busch Stadium to improve to 11-3 in his rookie Major League Baseball (MLB) season. His winning percentage of .786 is the highest by a rookie pitcher in Dodgers' history.
He lowered his ERA from 3.15 to 2.99, and didn't walk a single batter for his second straight start.
Ryu, a winner of five straight games, now has 118 strikeouts in 141 1/3 innings in 22 starts. He has pitched at least five innings in every start this season.
Ryu Hyun-jin of the Los Angeles Dodgers delivers a pitch during the road game against the St. Louis Cardinals on Aug. 8, 2013, at Busch Stadium. (AP=Yonhap)
Ryu has one more win than former Cy Young Award winner Clayton Kershaw, the Dodgers' No. 1 starter with a 10-7 record. Kershaw leads the NL with a 1.91 ERA and ranks second with 166 strikeouts.
Ryu has also pulled into a tie with Shelby Miller of the Cardinals for most wins by a rookie pitcher in the big leagues in 2013. Miller left Wednesday's game against the Dodgers in the first inning after he took a line drive to his right elbow, which could land him on the disabled list.
The Cardinals got their only run off Ryu in the fourth inning on an error by the Dodgers' center fielder Andre Ethier. It was scored as an unearned run.
The Cardinals entered the game as the NL leaders in runs scored, hits and batting average, but had no answer against the crafty South Korean, who consistently fooled the Cards with his changeups and sliders.
The Dodgers took a 1-0 lead in the top third on a sacrifice fly by Adrian Gonzalez. The Cardinals then tied things up in the bottom fourth on a bizarre play.
With Matt Holliday on first, David Freese hit a routine single up the middle. Ethier bobbled the ball as Holliday reached third. Then Ethier's throw back to infield went over the head of second baseman Mark Ellis and deflected off the second base into no man's land, allowing Holliday to score.
The Dodgers went ahead for good in the top fifth, as A.J. Ellis hit a tie-breaking three-run shot to make it a 4-1 game. Jerry Hairston lined a pinch-hit single in the top eighth for an insurance run.
Ryu has performed much better at Dodger Stadium than on the road. He is 5-1 with a 1.83 ERA in 10 starts at home. After the win over the Cards, Ryu improved to 6-2 in a dozen away starts, but his ERA is a mediocre 4.09.
After the game, Ryu said although he didn't have his best fastball, he was able to get by with his breaking pitches.
"I am pleased to have thrown so well and won on the road," he said. "I also got lucky because our offense got some timely hits."
Ryu has repeatedly said that he values his ERA more than his win total, and said after Thursday's victory that he was happy to see his ERA dip below 3.00.
"I barely got it down to 2.99 today," he said. "I will try to keep it under 3.00 for the rest of the season."
The Dodgers improved to 64-50, and have won 17 of their past 18 games away from Dodger Stadium. They hold a 5.5-game lead over the Arizona Diamondbacks in the NL West. The Cardinals dropped to 66-48 and are four games behind the NL Central-leading Pittsburgh Pirates.