SAN DIEGO -- When he initially hit the ball, Jordan Luplow thought he was out.

The D-backs left fielder hit a line drive to center field with one out and a runner on first base in the third inning of Tuesday's 3-2 loss to the Padres in 11 innings at Petco Park. The ball left his bat at just under 98 mph.

"I hit it and I first thought he was going to catch it because it was kind of a nice line drive to center field," Luplow said.

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Padres center fielder Trent Grisham seemed to think the exact same thing as he started to his right and in to catch the ball.

The ball, though, appeared to have other ideas.

"Then I saw it start to knuckle and take a weird kind of turn and then I just kept running," Luplow said.

Indeed, Luplow kept running and running and running as the ball skipped past a diving Grisham and rolled all the way to the wall in center. As he came around second base, Luplow looked at third-base coach Tony Perezchica who was waving his hands frantically. That was when Luplow realized he just might get an inside-the-park homer.

"He just kept waving me and I was like I'm going, here we go," Luplow said.

Grisham picked up the ball at the wall in center and threw to the cutoff man -- second baseman Jake Cronenworth -- whose throw home sailed wide and would not have gotten Luplow even if it had been on target.

Luplow slid headfirst into the plate. Did he think he was going to be out?

"It was basically just me falling over," Luplow said. "Gassed."

It was Luplow's first professional inside-the-park homer and he said he could not ever remember hitting one before. He also could not remember when he last sprinted from home plate all the way around the bases.

"Your guess is as good as mine," Luplow said. "Little League, maybe? You know when you're the No. 9 hitter and you just keep running."

Luplow had a hand in a number of key plays during the game. There was the homer, of course, but also a fly ball in the third, a throw to nail Jorge Alfaro in the sixth and he was involved in the final play of the game when José Azocar scored from second on a single to left in the 11th inning for the walk-off win.

The fly ball is really the play that Luplow would like to have back. It came in the third when Ha-Seong Kim drove a ball deep to left-center. It hit off Luplow's glove for an RBI double.

"I took a good route," Luplow said. "I thought it was carrying a lot farther, but it almost started to come back toward me. It just hit off the heel of my glove. You know, I tried to make the play and I thought I was going to have to lay out for it and ended up getting under it quicker than I thought. I need to catch that ball."

In the sixth, after Eric Hosmer tied the game with a homer, Alfaro drove a ball into the left field corner that Luplow fielded and threw a strike to Josh Rojas at third to nail Alfaro and end the inning.

"I was surprised he went, being a catcher and not having the greatest speed, you know, catching all game," Luplow said. "But that wall is tricky out there and I think he knows that."

In the 11th, with one out and automatic runner Azocar at second and Hosmer at first, Alfaro lined a single through the hole at short. Luplow charged the ball and made a strong throw home, but it was just a tad too late to catch the speedy Azocar.