CINCINNATI -- The Mariners’ August ascent has yet to carry over into September, and all of a sudden, a pitching staff that’s carried the club into first place in the American League West is experiencing some rare vulnerability. 

Bryan Woo became Seattle’s latest starter with a hiccup on this 1-3 road trip, walking three batters and hitting another three all while experiencing diminished velocity on each of his three fastballs.

On a 90-degree afternoon at hitter-friendly Great American Ball Park, Woo was pulled after just 83 pitches over five innings, exiting after surrendering five runs that led to a 6-3 loss to the NL Wild Card hopeful Reds. Meanwhile, in Arlington, the Astros raced away to a 13-6 victory over the Rangers to tie Seattle atop the division.

Games remaining: at CIN (2), at TB (4), vs. LAA (3), vs. LAD (3), at OAK (3), at TEX (3), vs. HOU (3), vs. TEX (4).

Standings update: The Mariners are tied with the Astros for the AL West lead, with the Rangers one game behind. Seattle is currently the second-best division leader, meaning it would host a five-game AL Division Series vs. the winner of a Wild Card Series starting on Oct. 7.

“It's really hard to have success giving up those types of free bags,” Woo said. “I've got to learn from it.”

The rookie’s brightest spot occurred just after first pitch, when he fielded a swinging bunt from No. 3 hitter Spencer Steer that chopped high to the third-base side of the mound and looked headed for an infield single. Yet Woo corralled the baseball with his pitching hand and fired to first baseman Ty France while completing a 360-degree spin into foul territory, making one of the Mariners’ most athletic plays of 2023 look easy.

But from there, Woo labored. 

He generated just 15 first-pitch strikes to 26 batters, which correlated to free traffic for the Reds, who had just four hits against Woo but made him pay with a big one -- a three-run homer by Steer in the second. 

“He has a really good fastball, and he likes to throw it. For me personally, I wasn’t going to let that pitch beat me today,” Steer said. “Really, just trying to stay on that fastball. He throws it from a different [arm] slot and it jumps out of his hand pretty good. That’s his best pitch, and he wants to throw it.”

The other two knocks that led to runs -- RBI singles from Elly De La Cruz and Hunter Renfroe in the first inning -- were on pitches well outside the zone, highlighting an aggressive, swing-early approach from Cincy against the righty. 

It was just the 11th time in franchise history a Seattle starter hit three batters in an outing, tying the team’s all-time high, and Woo was the first since Taijuan Walker on Aug. 28, 2016, to do so. Woo’s victims were all among his first eight batters, two of which came around to score. Also, he didn’t record a strikeout.

After Woo left, Tayler Saucedo hit another batter, Luke Weaver issued another walk and Seattle’s defense committed two errors, leading to 10 baserunners who reached without a hit.

“We pride ourselves on not giving up free bases,” manager Scott Servais said. “I think we're one of the best in the league at doing it, and today we were not.”

Including Logan Gilbert’s seven innings of one-run ball in a losing effort on Friday, the Mariners’ rotation this road trip has surrendered 15 runs (14 earned) in 19 2/3 innings, with five homers, 25 hits, 14 strikeouts and five walks, correlating to a 6.41 ERA, 1.53 WHIP and .881 opponents’ OPS. 

With just three runs from Seattle’s offense, the Mariners lost their second straight game by at least three runs after going 40 games without a defeat by a margin that wide. It was the sixth-longest streak in MLB history and first since the 1999 D-backs.

Julio Rodríguez made history by becoming the first player to tally 25 homers and 25 stolen bases in each of his first two seasons, with a 411-foot, opposite-field blast in the fourth. But he struck out with the bases loaded twice, including a game-ending backwards K that left him in visible frustration with home-plate umpire Marvin Hudson.

Rodríguez also punched out in the seventh while representing the go-ahead run following an inning-ending K in the sixth from Eugenio Suárez, who punched out with a half-swing on an off-plate breaking ball as the tying run. 

"We had some pitches to hit,” Servais said. “We didn't get much going until we had a couple guys out in the sixth, bases loaded in the seventh, late rally in the eighth. But the first five innings, they kind of cruised through that. And in these games, you've got to put pressure on them early."