PHOENIX -- John Hester will always remember his major league debut.
Thanks to Hester, Wilton Lopez may want to forget his.
"That's a start that I can only wish for, and it came true," Hester said. "After that, I don't know what I'm going to do to follow up."
Pinch-hitting in the sixth, the 25-year-old Hester hit a 2-2 delivery from Lopez, also making his first appearance in the majors, an estimated 420 feet off the batter's eye in center field. The ball caromed back onto the field and wound up in Hester's locker.
When Hester got back to the dugout, he was mobbed by teammates who shoved him up the steps to answer a curtain call from the Chase Field crowd of 26,190.
"I was like, 'Oh my God, this is really happening,' so I got up and gave them a curtain call," Hester said.
Hester became the 101st player to homer in his first major league at-bat -- and the second Diamondback to do it this season. Gerardo Parra homered in his first game on May 13 against Cincinnati.
"The curtain call, his first appearance at this stadium ... I just think it was a great cap to a great night," Arizona manager A.J. Hinch said.
Hester awoke in Las Vegas, where Arizona's Triple-A Reno team was playing, and was called up to fill a roster spot that opened when the Diamondbacks dealt reliever Jon Rauch to Minnesota. Hester caught a flight to Phoenix, arriving at the ballpark around 2 p.m.
The Diamondbacks skipped batting practice, so Hester took a few cuts in the cage under the stands. He said he had time to settle in before Hinch summoned him to bat in the sixth.
"I had the adrenalin flowing," Hester said. "A little nervous, excited, kind of the culmination of everything I've worked after, and it just kind of all came together at the right time."
Fresh off an 11-0 victory over San Francisco in AT&T Park on Thursday night, the Diamondbacks rolled up 10 runs in the first three innings against the Astros. The blitz began against starter Yorman Bazardo (0-1), who gave up eight runs, eight hits and three walks in two-plus innings.
"He's just got to learn to command the zone with his fastball, and use his breaking ball and get it over," Houston manager Cecil Cooper said. "He didn't really have a breaking ball, I thought, tonight."
Houston took a 4-3 lead on Keppinger's two-run homer in the third off Arizona starter Max Scherzer (8-8). Then the roof caved in on the Astros.
The Diamondbacks' first seven batters in the third inning all scored.
Bazardo issued a walk and then gave up four straight hits, the last a two-run double by Parra.
Cooper brought in Lopez, who was called up from Double-A Corpus Christi earlier in the day when the club put righty Alberto Arias on the 15-day disabled list.
Lopez' flight landed at Sky Harbor Airport at about 5 p.m, and he made his major league debut 2 1/2 hours later.
Lopez gave up a single to fellow rookie Brandon Allen on his second pitch and then yielded a three-run homer to Romero, who deposited the ball into the pool area in right-center field.
Lopez pitched four innings, allowing six runs and eight hits.
"For the first time here, I had bad luck," Lopez said through an interpreter. "I'll be able to learn from this."
Former Diamondbacks OF Luis Gonzalez will announce his retirement at a news conference on Saturday. Gonzalez is joining Arizona as a special assistant to president and CEO Derrick Hall. ... After singling home a run in the second, Drew was caught in a pickle between first and second and retired on a 9-1-6-4-6-1 putout. ... The Astros said LHP Wandy Rodriguez (12-8, 2.82 ERA) would pitch Sunday's series finale against Arizona ace RHP Dan Haren (12-8, 2.73 ERA).