ARLINGTON -- Given the A's just won their 90th game of the season, it's fair to say they managed pretty well without Sean Manaea while the lefty was rehabbing from last year's shoulder surgery.

But if Manaea pitches as well as he has through his first three outings since being activated from the injured list on Sept. 1, the A's postseason outlook could look even better than originally thought as they inch toward the end of the regular season, which ends in two weeks.

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The A's topped the Rangers on Sunday at Globe Life Park, 6-1, sweeping the series and maintaining their stronghold on the top spot in the American League Wild Card race. They did this behind the strength of two of the most intriguing figures on the A's roster to date -- Manaea, one of the club’s rising stars in a talented starting rotation, and Jesus Luzardo, who got out of a potentially disastrous bases-loaded, no-out situation in the eighth to dominate the final three batters and maintain Oakland's somewhat comfortable lead.

In three starts, Manaea has allowed one earned run across 18 innings. That’s a 0.50 ERA to accompany a 0.67 WHIP. He’s also struck out 21.

“Every time out, it's borderline dominance,” manager Bob Melvin said.

The significance of all of this goes far beyond one outing. The A’s, with an eye on October, have a strong rotation that is six deep, which has allowed them to give every one of their starters proper rest. This comes at a time when other contending teams are navigating through injuries to key starters and tired, overworked bullpens.

Manaea, having missed five months of the season, may be the freshest arm in the entire playoff pool, assuming Oakland gets there.

“We don't have to worry about being run down, we're even giving him a week in between starts and can probably cut that back -- I'm not sure,” Melvin said. “Unfortunately, he had to go through what he had to go through to get to this place, but it's a fresh, live arm right now and every time he goes out there, the team just feels better about themselves.”

“This is what I’ve been working for,” Manaea said. “I’m happy to contribute in a way to help this team. Everybody’s been grinding out this whole year, and to come here and provide some relief is, I think, huge.”

Manaea wobbled through a 25-pitch first inning, but didn't let that bleed into the rest of his start. The lefty hit the first batter he faced, Shin-Soo Choo, and yielded a base hit to Elvis Andrus. Willie Calhoun grounded into a double play, and after Nick Solak walked, Manaea fanned Rougned Odor, the first of Manaea’s six strikeouts on the day.

From there, Manaea cruised. Two Rangers baserunners reached from the second inning through the end of the left-hander's outing. Choo singled in the third and the sixth, but was stranded at first both times.

“I think that was the best my fastball felt, good location,” Manaea said. “I don’t know about the velo, but everything felt like it was on time and I was able to locate things better.”

It was exactly the type of outing Oakland needed. Neither starter in the first two games made it to the fourth inning. That led to the bullpen being a little thin heading into the series finale -- and that’s where Luzardo “saved” the day.

The electric rookie lefty worked in and out of a mess in an eighth inning that featured a double, a single, two walks, a passed ball and a wild pitch. Luzardo recovered to strike out Solak and Odor on sliders, before Scott Heineman grounded out to end the inning.

“Just kind of step back, take a breath, slow it down,” said Luzardo, who logged his first career save. “Go pitch by pitch. I was going a little fast there. I'm glad I was able to get back on my feet.”

Melvin said he found out more about Luzardo in that sticky inning than he ever knew up until now.

“When you have that kind of stuff, you back off, you worry about one particular pitch. He's got a strikeout in his back pocket, he's got a ground ball whenever he needs it, with the two-seamer,” Melvin said. “His strikeout numbers and his ground-ball rate are all off the charts. That's what the elite guys do.

“It was good to see him get through that inning, and he had no part of wanting to come of that game. He came in the dugout, he let me know he had the ninth.”