Running on contact from third base, the D-backs' right fielder saw the ball being hit to Troy Tulowitzki at short, and he knew that meant there was going to be a play at the plate.
It was right then he decided he was going to run Rockies catcher Chris Iannetta over if the play was close.
"I told myself beforehand I wasn't going to pull up on that play and let him tag me," Upton said. "He was going to have to earn it. I know that since it was hit to Tulo the ball was going to get to the plate pretty quick."
Upton smashed into Iannetta, who hung onto the ball for the out. Later Ianetta would call it a "clean" play, and Tulowitzki did likewise.
"That was aggressive baserunning on their part, a ground ball to me, to still go," Tulowitzki said. "He was coming in full speed. I know he hit Chris the way he did, but Chris is tough back there. It was good baseball all the way around."
Even though Upton was out, the play brought a smile to Arizona manager Kirk Gibson's face.
"Anybody question's Justin Upton and what he's here for, the way he went into that catcher [Friday], I think it's pretty obvious," Gibson said. "That kid played his heart out."
It's the kind of hard-nosed baseball the D-backs are determined to play this year.
"We have to go get after people," Upton said. "We're the type of team that has to grind for every win that we get. Plays like that are going to define a team, so to get one on Opening Day was nice."