Denver — Marcelo Mayer’s fielding miscue in the seventh inning played a pivotal role in the Boston Red Sox’s 8-6 loss to the Colorado Rockies on Wednesday, marking another setback during their road trip. The defeat prevented the Red Sox from sweeping the series against the team with the worst record in Major League Baseball, leaving Boston at 32-46 and on pace for a season total of 96 losses.

The game’s turning point came in the top of the seventh inning. The Red Sox held a lead when reliever Tyron Guerrero entered in relief of starter Ranger Suarez, who had pitched six innings while allowing three runs (two earned). Guerrero promptly retired three Rockies batters, including a strikeout of Willi Castro and a flyout from TJ Rumfield, making it appear the inning was over.

However, Hunter Goodman hit a ground ball to Mayer at shortstop, who was making his first appearance in that position after a defensive reshuffle prompted by an injury. Mayer committed an error on the routine grounder, failing to complete the transfer and flip to second base for the inning-ending out. This extended the inning and allowed the Rockies to seize momentum.

“We were out of the inning,” Guerrero said. “And then something happens.”

Following the error, Guerrero faced Cole Carrigg, who delivered an RBI single on a pitch that stayed in the strike zone despite Guerrero’s intention to bury it in the dirt. Next, Jake McCarthy singled again, driving in another run on a 102.3 mph sinker that failed to find its intended location. Manager Chad Tracy then brought in left-hander Danny Coulombe, but Troy Johnston hit a single to center field that tied the game.

Mayer took responsibility for the error, describing it as “a brutal error” on what he called “the most routine ground ball” he could receive and acknowledging that it “ended up costing us the game.” Sitting in the clubhouse after the game, Mayer appeared visibly frustrated and disheartened, expressing remorse to teammates and reflecting quietly.

The defensive adjustment that placed Mayer at shortstop was necessitated by an injury to teammate Caleb Durbin, who suffered a left fifth finger subluxation sliding into first base earlier in the game. Durbin’s finger was promptly reset, allowing him to avoid time on the injured list, but his exit required Mayer to take over at shortstop. Additional defensive lapses contributed to the Rockies rally that ultimately overcame the Red Sox’s early lead.

The Rockies improved to 32-49 with the win, while the Red Sox face growing concerns over their inconsistent performance amid a challenging season.