BOSTON -- For five innings on Friday night, facing one of the top lineups in the Major Leagues, Tanner Houck appeared on the verge of one of his finest starts of the season.

But then came that familiar foe known as the sixth inning. And that other hurdle Houck has struggled to clear -- the third time through the batting order.

The Orioles took Houck (4-9, 5.28 ERA) out of the game in the sixth inning by erupting for a four-spot en route to an 11-2 victory over the Red Sox.

It was a sharp turn of events for a game that was 1-0, Baltimore, through five.

This was the second start in a row that Houck was touched for three runs or more in the sixth.

“Need to get better. Need to execute pitches a little bit better,” Houck said. “Need to clean it up a little bit. All in all, continue to learn and push myself to get better each time. Continue to work.”

With 21 games left in the season, the Red Sox (72-69) have lost three in a row and their postseason hopes are fading. Boston trails Toronto by six games for the third American League Wild Card spot.

As the odds continue to mount against the Red Sox, development will be more of a priority these final three weeks.

One player to watch in that regard is Houck.

In the eight times Houck has pitched into the sixth inning this season, he has recorded 15 outs for manager Alex Cora while allowing 11 earned runs.

“He’s got good stuff. We’ll find a way because this kid, his stuff is good,” Cora said. “The cutter was good today, the sinker, the slider. So, he’s just got to keep working. We’ll push him out there and go as long as possible, and we’ll find a way.”

When facing the order a third time, which often coincides with the sixth inning, Houck has been roughed up to the tune of a .297 batting average and a .924 OPS to go along with a 9.98 ERA.

“I’ve just got to continue to stick with my strong suits the best I can,” Houck said. “I felt like I've grown as a pitcher in terms of being in the zone more [and] attacking hitters earlier. And just trying to go deeper into games and understanding the development side of that.

“And pitch sequencing and all that, so it's forever an evolving process. Day by day, you're not going to have certain pitches. So you gotta lean on other pitches a little bit more. But pushing myself to get through the lineup three times, go deeper in the game and go six, seven innings [is the key].”

Houck put himself in a bad spot to start the sixth when he walked Anthony Santander.

“Today, I would definitely say command,” Houck said. “Leadoff walk is definitely unacceptable. That kind of snowballed the inning.”

The Red Sox remain optimistic about what the 27-year-old with the mid-90s fastball and a nasty slider can do for them going forward.

“He was good [before the sixth],” Cora said. “Threw the ball well. There was some traffic the third time around, and he tried to go two-seamer in to [Cedric] Mullins, and he put a good swing on it. But stuff was good, and he had some swing and miss [stuff].”

The big righty hit a roadblock that was through no fault of his own this season when he sustained a facial fracture on June 16, when he was struck by a batted ball by Kyle Higashioka of the Yankees.

Houck lost more than two months in Boston’s rotation due to that injury, making his return to action on Aug. 22.

Friday night marked Houck’s fourth turn in the rotation since his return, and the 5 1/3 innings he pitched against the Orioles represented his lengthiest start since going six innings against the Yankees on June 10.

Houck figures to get four more starts before the season ends. It is clear what his key area of focus will be.

“As a competitor and someone that wants to go deeper, wants to do everything I can to help the team win and do it for the team, do it for the guys, do it for the city, it’s hard,” Houck said. “I want to go out there and perform at a high level, and I did that for five innings. Sixth inning got away.”