BOSTON -- The defending World Series champion Red Sox were in trouble from the first pitch against their 2018 postseason foe.

Hector Velázquez opened Saturday night’s game with a 91.2 mph sinker to Astros leadoff hitter George Springer, who crushed it 399 feet off the center-field wall at 103.3 mph, per Statcast; the ball eluded a chasing Jackie Bradley Jr. for a triple that set the tone for the rest of the inning.

• Box score

“They hit a triple, I made a couple mistakes, and I tried to battle through it, but I couldn’t,” Velazquez said through an interpreter.

Velazquez gave up three runs before he was pulled after one-third of an inning and 30 pitches in Boston's 7-3 loss at Fenway Park. The only out he recorded was a sacrifice fly by Josh Reddick. He was replaced by Colten Brewer with runners on first and second, and was charged with two additional runs after the first hitter Brewer faced, Tyler White, hit an RBI double.

“At that point it didn’t seem like he had good stuff,” manager Alex Cora said. “He wasn’t pitching to the edges, it was in the middle of the zone. So we went with Brewer. That pitch down the zone to White [had] a good swing on it, and they scored five. That was it.”

The Red Sox had won Velazquez’s last three starts, but this quick outing didn’t yield the same result. Instead the Astros extended their winning streak to 10 games.

Velazquez (1-3, 5.53 ERA) allowed five earned runs on three hits and two walks, and didn't record a strikeout. He became the first Red Sox starter since John Burkett on Sept. 24, 2003, to give up five-plus runs in one-third of an inning or less.

Velazquez's abbreviated outing came on the two-year anniversary of his Major League debut, with the Athletics. He noted that he struggled that day, too, giving up six earned runs over five innings.

Velazquez has made 13 appearances this season, seven of them starts. There are challenges with the shifting in roles, although he doesn’t let himself get caught up in them.

“The tough part is sometimes I have to relieve in between starts and not knowing if I’m going to start,” he said. “But it’s on me to come out and make good starts.”

If the Red Sox stay on rotation, Velazquez’s next start could be in the upcoming Blue Jays series. Cora wasn’t jumping to make immediate changes after the loss, noting how well the Astros are playing.

“Wait and see,” Cora said. “That spot doesn’t come up until the last day in Toronto. We’ll talk about it the next few days and go from there. It’s just a bad [start].”

The Red Sox attempted to chip away at the Astros’ lead throughout the night. J.D. Martinez scored on a bases-loaded passed ball by catcher Max Stassi in the first, and Mitch Moreland doubled to drive in Mookie Betts in the third. The following inning, Christian Vázquez connected on a 311-foot solo homer to right field, the shortest non-inside-the-park home run of the year. But with the score 7-3, the Red Sox left the bases loaded in the fifth.

The Red Sox have dropped two straight to the Astros and lost their first series since a two-game sweep by the Rays last month. They will look to bounce back on Sunday afternoon, and will see the Astros again soon after that, as they travel to Houston for a three-game series starting May 24.

“Maybe we can calm them down tomorrow and they get on a cold streak,” Xander Bogaerts said. “That’s what happens. You go hot, and then you go cold. We caught them at a bad time right now, but hopefully we get them on our advantage next time.”