Gregorius hit his second major league home run and singled to start a two-run rally in the ninth inning that led Arizona over Colorado 5-4 Sunday and stopped the Rockies' eight-game winning streak.
Gregorius, who homered Thursday at Yankee Stadium on the first pitch he saw with the Diamondbacks, started a comeback from a 3-0 deficit when he homered against Juan Nicasio leading off the fifth.
"I am battling every at-bat," said Gregorius, who was acquired from Cincinnati as part of a three-team trade in December. "I work each day to prepare for every game. I never give up."
In his first three games with the Diamondbacks, Gregorius has gone 6 for 11 with a pair of homers and a double.
"He sees the ball well," Diamondbacks manager Kirk Gibson said. "He has a real good approach with two outs. He's a tough out. He doesn't surprise me. We thought a lot of him, obviously. We traded him for him."
Colorado led 4-3 when Gregorius singled leading off the ninth against Wilton Lopez (0-1). A.J. Pollock doubled over third baseman Jonathan Herrera, and pinch-hitter Alfredo Marte grounded out to third, driving in the tying run. Gerardo Parra followed with a sacrifice fly to deep center.
"The whole bullpen gave us a chance," Bell said. "Matt Reynolds did well before me. And J.J. after me. We wanted to keep the ball down. The Rockies were on fire. And we knew we had to make pitches."
Arizona improved to 6-0 in getaway games this year.
Colorado lost for the first time in nine games at Coors Field. Rockies manager Walt Weiss said before the game that he hoped to avoid using closer Rafael Betancourt for a third straight day.
"This is a good team and we battle every single game," said the Rockies' Carlos Gonzalez, whose two-run single boosted his league-leading RBI total to 21.
"If you're going to lose your winning streak, it's better to do it the way we did today, playing good baseball," Gonzalez added. "We just had one bad inning at the end. Our closer was not available today, but I know that Wilton is going to get better. He's just having a bad start. But he's done it in the big leagues. he's going to pitch well."
The Rockies had a bit of a spring training feel in the middle innings, judging by uniform numbers. Adam Ottavino, No. 0, relieved starter Nicasio in the fifth and Josh Outman, No. 88, got the last two outs of the seventh.
Colorado strung together four consecutive singles in the third off Brandon McCarthy, building a 3-0 lead on Jordan Pacheco's RBI single and Gonzalez's bloop two-run single that dropped into shallow center field.
Nicasio struggled with his control despite not allowing a hit until the fifth. He threw 49 pitches in the first two innings, when he walked three and went to three-ball counts on two other batters.
"I need more command of my fastball," Nicasio said. "I've thrown like 90 pitches in the last three games and only gone five innings. I've got to go deeper in the game."
Gregorius homered off Nicasio to start the fifth for the Diamondbacks' first hit, and Pollock's single and Parra's one-out doubled chased Nicasio. Martin Prado reached on a comebacker to Ottovino, who tagged out Pollack after the runner broke for home, and Paul Goldschmidt followed with an RBI single that cut the gap to 3-2.
Troy Tulowitzki homered on a 1-2 pitch leading off the sixth, and with six home runs already is just two shy of his total last year.
Eric Young Jr. caught the ceremonial first pitch from his younger brother Dallas and his father, former Rockies player Eric Young, on the day the club honored the senior Young with a bobblehead doll giveaway. ... McCarthy allowed four runs and eight hits in six innings. ... The Diamondbacks return home to face the San Francisco on Monday with LHP Wade Miley (2-0) slated to pitch the opener against the Giants' Ryan Vogelsong (1-1). ... Colorado opens its series against the Braves on Monday with LHP Jeff Francis (1-1) facing Atlanta's LHP Mike Minor (2-1). ... The Rockies placed Jhoulys Chacin on the 15-day DL with a back strain, a move retroactive to Saturday. They recalled RHP Rob Scahill from Triple-A Colorado Springs.