Masterson (2-6) allowed one run on five hits while striking out six in seven innings pitched. His only damage came on a solo shot by Carlos Beltran in the third inning.
Beltran hit Masterson's 1-0 pitch an estimated 410 feet, just over the wall in center, to put the Cardinals up, 1-0. It was Beltran's National League-leading 17th homer of the season, and the seventh homer Masterson's allowed this year.
Beltran made Masterson pay for hanging a slider up, but the right-hander was pleased with the way his slider was breaking all day. His sinker was moving as well, and he was hitting his spots with his four-seamer. Masterson sounded just about as happy as a starter could be after losing a game.
"You can't beat yourself up," Masterson said. "I made one pitch that I kind of hung it up there, and Beltran is a good hitter. You could tell it was his day. I kept it as close I could. I was ready to go out there for the eighth inning if I was needed."
Masterson threw his seventh quality start of the season, and allowed no more than one run in a start for the third time this year. He also didn't allow a walk for the second straight outing.
"He obviously kept us off-balance," Cardinals manger Mike Matheny said of Masterson. "We knew we were coming against a guy with a good sinker and he pounded the bottom of the zone and you could see that he was on, because we had a lot of ground balls right from the start. He has good stuff, no question about it."
On Friday the Indians backed their starter -- Josh Tomlin -- with 11 hits. But the run support was not there on Saturday.
"It definitely wasn't a fun night," Indians left fielder Johnny Damon said. "It's amazing that the night's over, and I just feel bad for Masterson. He went out and threw the ball well, and we just couldn't get much going."
Lohse walked two and struck out four in his first win against the Indians since 2004 while working in a relief role.
The Indians had their best scoring opportunity in the fourth, putting men on first and second with one down. Carlos Santana walked, and Michael Brantley followed with a bunt single down the third baseline to extend his hitting streak to 17 games. Lohse got Damon to pop out and Casey Kotchman to ground out to end the inning.
"[Lohse] seemed like he put his fastball, or I should say all of his pitches, exactly where he wanted to all the time," Damon said. "He definitely out-guessed us a little bit. Normally a guy like that keeps the ball down quite a bit, but I think his most effective pitches were the ones that were up."
While Lohse kept the Indians guessing, they weren't too far off when they swung their bats. Lohse induced only two swinging strikes all night.
Leadoff batter Shoo-Sin Choo, for example, was 0-for-4 with four hard-hit balls right at Cardinals defenders. But as any manager knows, that's part of baseball.
"That's all you can do. All we ask these guys to do is to have quality at-bats," Indians manager Manny Acta said. "You hit the ball hard and then after that, you can't control the rest."
Asdrubal Cabrera bounced Lohse from the game with a two-out single off the wall in the eighth. Cabrera was caught stealing on the next pitch, however. He is 2-for-5 this season on stolen base attempts.
Like Masterson, Acta also took solace in the loss. His club was one of just two teams left in the Majors -- along with Detroit -- to have not been shut out in a game this year. By June 9 last season, the Indians had already been shut out six times.
"A step in the right direction," said Acta. "It took over two months for us to get shut out. It's a credit to the guys. They've been battling, and it had to happen."