PHOENIX -- When the ball left Marcus Semien¡¯s bat, Paul Sewald cringed before starting to move off the mound to back up third base.

¡°That¡¯s where you¡¯re supposed to go when someone hits a triple,¡± Sewald said.

In the dugout, D-backs manager Torey Lovullo couldn¡¯t see exactly what was happening that far away, so he just listened for the crowd noise.

In center field, though, Alek Thomas was confident he was going to catch it.

¡°Yeah, definitely had a good bead on it,¡± Thomas said. ¡°Put my head down and just ran where I thought it was gonna be and looked up and I knew I had a chance and I lunged for it.¡±

Thomas lunged, caught the ball and tumbled onto the warning track in right-center, the deepest part of Chase Field.

In the dugout, outfielder Lourdes Gurriel Jr. put his hands on his head in disbelief. Reliever Kevin Ginkel tipped his hat. Starter Zac Gallen, going through his post-start work in the clubhouse, let out a cheer.

Sewald would still have to survive the rest of a dicey ninth inning, but that first out gave everyone wearing an Arizona uniform a jolt of energy as they hung on for a 6-3 win that moved them into the final National League Wild Card Spot, mere percentage points behind the Cubs and half a game ahead of the Reds and Giants.

The win was the ninth in the past 11 games for the D-backs, who had lost 25 of 32 before that.

¡°I was just thinking triple off the bat and [that it was a] good thing we had a three-run lead and didn't have to worry about it,¡± Sewald said of the play. ¡°Extra special since it got a little bit away from me there for a little bit. So thank you, A.T.¡±

The Rangers would go on to load the bases after that out, but Sewald was able to retire the next two hitters to secure his sixth save in seven chances with the D-backs.

¡°It gets a little blurry for me out there,¡± Lovullo said. ¡°[Thomas] has got his back to me and it's against a different setting, and I just listened for the crowd reaction and he's on the ground running into the fence. I thought it was pretty, pretty darned good play. There¡¯s been some unbelievable plays that I've seen, but I'm gonna say that's the top of the list, for sure.¡±

Coincidentally, it wasn¡¯t the first time that Thomas had spent time running in an outfield tracking down a fly ball hit by Semien.

Thomas¡¯ dad, Allen, was the longtime strength and conditioning coordinator for the White Sox, and when he was younger, Alek would shag balls during batting practice.

¡°It's funny that it was against someone that I know and have shagged balls against before,¡± Thomas said. ¡°Marcus was drafted by the White Sox and I grew up watching him hit BP all the time, so I know his swing a little bit.¡±

According to Statcast, Thomas covered 101 feet with a sprint speed of 30.2 feet per second, which is considered elite.

¡°I just thought it was really funny that I ended up making that catch because of how far I had to run,¡± Thomas said. ¡°I mean, I think my sprint speed is down a little bit this year, but hopefully, that'll put it up a few notches.¡±

Sewald, meanwhile, would like to not make a habit of loading the bases in situations like that.

¡°We're going to try and mix in some 1-2-3 innings and kind of calm these innings down,¡± said Sewald. ¡°That was a little scarier than we needed to make it.¡±