CHICAGO -- It was looking like Jordan Montgomery was headed for another quality start after cruising through four scoreless innings. The Cardinals were also in a great spot, leading the White Sox by five runs.

Then, it all fell a part.

Montgomery left the game with a hamstring injury after 4 1/3 innings, and the bullpen blew the lead twice in the Cardinals’ 8-7 loss on Friday evening at Guaranteed Rate Field. That’s now the team’s 20th blown save of the season and its 19th one-run loss.

It was also the first time since Opening Day (March 30) against the Blue Jays that St. Louis blew two save opportunities in one game.

“We’ve been there before,” manager Oliver Marmol said. “We’ve had the lead more than twice in certain games and blown it. With our pitching staff, we can’t give away outs, and we did a decent amount of that today.”

Montgomery entered Friday with a 1.38 ERA across his last five starts, allowing just five earned runs across 32 2/3 innings since June 3. He was looking for his sixth straight quality start.

And early on, it appeared that the bullpen wasn’t going to pitch many innings.

The southpaw allowed just one hit and one walk through four  innings before running into some trouble in the fifth. He allowed a solo homer to Jake Burger and a double to Zach Remillard, the next batter.

Then, Montgomery grabbed at his leg on a 2-1 pitch to White Sox second baseman Elvis Andrus and left the game with a hamstring injury. His day was done at just 4 1/3 innings of one-run ball on 66 pitches.

“Pretty good,” Montgomery said of his outing before his exit. “I was pretty much in control every at-bat. I let one come more middle to Burger [for the home run]. But it was a full count, and I just wanted to go after him. Yeah, I was cruising.”

Montgomery will get imaging done on Saturday. He doesn’t want to assume anything yet about the results.

“Hoping for some good news,” the left-hander said. “I just kind of slipped on the mound, and my body tried to catch myself. I don’t want to say anything yet. Just hoping for good news tomorrow.”

Following Montgomery's exit, St. Louis quickly saw its lead vanish. JoJo Romero and Andre Pallante combined to allow five runs in the sixth, and Pallante might have been tipping his pitches in the inning.

“[White Sox catcher Yasmani] Grandal was relaying signs from first,” Marmol said. “He was telling the hitter what was coming. He made it pretty obvious, so we went out there… to tighten that up.”

Even with Nolan Arenado trying to play hero ball by crushing the go-ahead two-run homer in the seventh to take a 7-6 lead -- for his second long ball of the game -- the bullpen gave the lead right back in the bottom half of the inning to essentially seal the game.

“[Giovanny] Gallegos was down,” Marmol said. “With Monty going down early, it forced us to go to the ‘pen, and here we are.”

The bullpen has been a problem for the Cardinals all season, and Friday was another example of it. St. Louis relievers have now blown saves in three different games this week: Monday’s 5-4 loss, Wednesday’s 10-9 loss, and Friday’s 8-7 loss.

The Cardinals entered the game with a 4.46 bullpen ERA, seventh-highest in the Majors. After allowing six more earned runs over 3 2/3 innings on Friday, not one reliever on the team (with more than 10 innings pitched) has an ERA lower than 4.00.

“[Montgomery] was having a great day, but this injury happened,” Iván Herrara said following a two-hit, two-RBI performance. “He was commanding really well. It’s a tough loss.”

The loss dropped the Cardinals to 16 games under .500 and 12 1/2 games back from the Reds in the National League Central. The team and Montgomery now await the news of his hamstring injury on Saturday, hoping for positive results.

“He’s been really good and yeah, it hurts,” Marmol said. “This is a guy that’s been giving us a chance every time out.”