Not only did the Giants right-hander go fewer than six innings in both starts for the first time this season, but he lost back-to-back contests for just the second time this year.
He'll try to get back to his winning ways Saturday, when the Giants take on the Rockies at AT&T Park.
Allowing seven runs in 10 2/3 innings over his last two starts, Cain tossed 5 2/3 innings against the Cardinals on Monday, surrendering five runs on eight hits.
While his ERA is over four since his June 13 perfect game, Cain said he still feels good about the way he's been pitching.
"I'm going out there to try and do my job," Cain said. "There's times you give up maybe more pitches in different games. I guess it's just make better pitches and get quicker outs."
Meanwhile, Drew Pomeranz will take the hill for the Rockies after keeping the Dodgers' bats in check during his last start.
The left-hander held the Dodgers to just three hits in four innings Monday, striking out seven and walking just three.
"My mechanics weren't the greatest, but I made it work and gave it everything I had," said Pomeranz, who threw 84 pitches in the four frames. "I wish I had thrown a few less pitches, but it happens.
"I threw my off-speed for strikes, but I was a little off with my fastball."
Rockies: Tulowitzki increases workouts
As part of his comeback from left groin surgery in June, shortstop Troy Tulowitzki went through his toughest day Friday, with a grueling set of movement exercises -- running and lateral movement, among others -- administered by head athletic trainer Keith Dugger at AT&T Park.
"We signed up for this because we want to be out there on the field, so just watching is tough," Tulowitkzi said. "Then you have to rest and you get a little bit out of shape, so they put a whole bunch on your plate to try to catch up. That's what they're doing with me."
Tulowitzki, who hasn't played since May 30, said beyond normal soreness that comes with heavy physical work, he feels good. His next major step will come when the team returns to Denver next week and Tulowitzki fields balls and make throws to first base the way he would in a game.
First baseman Todd Helton's season-ending surgery on his right hip went as expected Friday. The operation, performed by Dr. James Genuario in Englewood, Colo., was to repair a torn labrum and other damage, but nothing unexpected was found, manager Jim Tracy said. Helton, who turns 39 on Aug. 20, hopes to be ready for next Spring Training.
Giants: Sandoval eyeing Monday return
Pablo Sandoval began his rehab assignment with Class A San Jose on Friday night, and if all goes as planned, the All-Star third baseman could rejoin the Giants as early as Monday, manager Bruce Bochy said.
"We'll see how it goes," Bochy said Friday. "He's playing five innings in San Jose, and if all goes well, then we'll push it to seven. So possibly it could be Monday, but we'll have to evaluate him after tonight's game and tomorrow's game."
Sandoval, who went 0-for-2 while playing five innings at third base Friday, has been sidelined since July 25 with a strained left hamstring, which he injured while playing first base.
Rockies first baseman Jason Giambi, who hasn't played since July 20 because of viral syndrome, has begun playing catch, running and working in the weight room but is still waiting for his energy to return.
Since the All-Star break, Giants catcher Buster Posey has hit safely in 22 of 25 games, batting .441 (41-for-93) with eight home runs and 30 RBIs.