BALTIMORE -- Shane McClanahan knew facing the Orioles for the fourth time in less than six weeks would be a test. Having developed some familiarity with Tampa Bay’s young left-hander, Baltimore’s hitters didn’t chase many pitches outside the strike zone Friday night. They put balls in play and hit a lot of them hard.

But McClanahan, backed by another excellent defensive performance, still passed the test. The left-hander held the Orioles to two runs over six innings in the Rays’ 6-3 win on Friday night at Camden Yards, wrapping up a month in which he went 5-0 with a 2.76 ERA in another display of his evolution as a starting pitcher.

• Box score

“Anytime you can go six innings, give up two runs and keep your team in the game is a pretty good night, I would say, in the big leagues,” McClanahan said afterward.

McClanahan’s six-inning effort, Mike Zunino’s three-run homer in the seventh inning and defensive gems by Kevin Kiermaier and Wander Franco highlighted the Rays’ fifth straight victory as they improved to 80-48, the first American League team to reach the 80-win mark. Sixteen of those wins have come in their 17 matchups against the Orioles this year, setting a single-season club record for most wins against one opponent.

Tampa Bay jumped out to an early lead, scoring three runs on Franco’s walk followed by four straight hits with two outs in the first inning against right-hander Matt Harvey, before Harvey bounced back to retire 16 straight batters. Zunino gave the Rays a more comfortable lead in the seventh, launching his 27th homer of the season a Statcast-projected 453 feet to center off lefty reliever Tanner Scott.

But the early advantage was enough for McClanahan, who was making his fourth start against Baltimore in the last 39 days

He breezed through his first three innings against them on only 30 pitches, but the Orioles made him work in a 26-pitch fourth during which he allowed a two-run homer to Austin Hays. With two outs and two runners in scoring position, McClanahan froze Jahmai Jones with a slider to escape the jam.

“I thought he did a good job. He mixed all four pitches, battled a little adversity … and I thought he responded really well,” Zunino said. “That's what you want, to get tested this late in the season to see what it's about, and he responded really, really well.”

From there, McClanahan leaned on the Rays’ excellent defense to get through the sixth. It was the lefty’s 13th straight outing allowing three runs or fewer, the 11th time in his last 12 starts that he completed at least five innings and his fifth straight win in August, tying the club record for most individual victories in a month.

“They did him no favors by expanding [and swinging outside] the zone,” manager Kevin Cash said. “So I thought Shane recognized that, ‘I've got to throw strikes and let the defense work behind me.’ I think that's big for him and us.”

Friday’s performance was another good illustration of why the Rays think so highly of McClanahan and the work he has put in to develop into a complete pitcher.

Once thought of as a two-pitch starter, the lefty continued to display a true four-pitch mix with 31 fastballs, 24 sliders, 17 curveballs and six changeups, and he produced at least one swinging strike on each offering. He pounded the strike zone, throwing 53 of 78 pitches for strikes and going without a walk.

“That’s one thing I’m very proud of the last two, three months that I’ve been able to do is [throw] any pitch in any count,” McClanahan said. “Anytime you can fill up the zone all night like I tried to do, you’re going to hopefully be in a good spot at the end of the day.”

In short, the 24-year-old rookie possesses a combination of elite stuff -- a fastball in the mid to upper 90s plus three swing-and-miss secondary offerings -- and a willingness to attack hitters with it. Lately, that has been a recipe for success that he hopes to carry into the final stretch of the season.

“When you draw it up as the prototypical starter, he's that guy -- with plus stuff,” Zunino said. “His ability to be able to fill up the strike zone and mix his pitches is what's going to let him do this for a long time. It's going to let him have quick innings. And when he does that and he gets on a roll, he's something special.”

Special is also a good word to describe the Rays’ defense behind McClanahan on Friday. When he was asked after the game about the defense the Rays played behind him, he simply pointed at the one word on his T-shirt -- “GOOD” -- and smiled.

Franco made a leaping, reaching catch to rob Ryan Mountcastle of a hit to begin the fourth inning. He snared a hard-hit grounder by Kelvin Gutierrez then quickly spun and made a strong throw to first base for the first out of the fifth. The Rays also turned a pair of double plays, including a big one from Joey Wendle to Brandon Lowe to Yandy Díaz to end the sixth.

But the defensive highlight of the night belonged to Kiermaier. With the Rays hanging on to a one-run lead and a runner on first base in the fifth, Mountcastle launched a high fly ball to deep center field. Kiermaier tracked the ball as he worked his way back toward the outfield wall, left his feet and robbed Mountcastle of a go-ahead homer.

“I felt like every single inning, I was having to turn around and tip my cap at somebody,” McClanahan said. “It was awesome.”