Making his first start since a terrifying neck injury last August, Nicasio allowed one run on five hits in seven innings in Colorado's 3-2 loss to Houston on Sunday.
"I wasn't nervous, I was feeling good," Nicasio said. "Thank you God, because I wanted to have the opportunity to get to the mound, I want to go to compete. Just get it out of the way. It's time."
Nicasio struck out four with only one walk, but Colorado couldn't hold the lead.
Rex Brothers (0-1) relieved Nicasio for the bottom of the eighth, when Colorado led 2-1. With two outs, Jose Altuve singled and J.D. Martinez beat out a grounder hit so sharply back to Brothers that it knocked off the pitcher's glove. Brian Bixler came in to run for Martinez.
Third baseman Jordan Pacheco then backhanded Carlos Lee's grounder, but threw wildly to first, and Altuve scored to tie it. Brian Bogusevic singled to right on the next pitch, Bixler trotted home and Houston took a 3-2 lead.
"I didn't get a good grip on it and threw it away," Pacheco said.
Wilin Rosario hit a two-run homer earlier for the Rockies, who mustered only four hits off Houston starter Bud Norris. Astros' reliever Wilton Lopez (1-0) finished the eighth, and Brett Myers pitched a scoreless ninth for Houston to earn the save.
"Because of our inability to do anything offensively other than the one swing Wilin Rosario took, we put ourselves in a position where any little mistake that gets made is going to get magnified, and potentially cost us the game," Colorado manager Jim Tracy said. "And that's exactly what happened."
Colorado was seeking its first series win in Houston since 2008. The Rockies got solid starting pitching in two of the three games, a positive sign as they head home to open a series with San Francisco.
"Around the league, offenses start kind of slow," Troy Tulowitzki said. "The pitching kind of dominates at the beginning. That held true for this series, at least. It wasn't very offensive."
Despite the loss, Tulowitzki said Nicasio's return gave everyone in the Colorado clubhouse a boost.
Nicasio, 4-4 in 13 starts as a rookie last season, was hurt last Aug. 5 when a line drive by Washington's Ian Desmond hit him. He underwent surgery to have two pins inserted into his cracked C-1 vertebra and also had a small metal plate attached to the back of his neck.
Nicasio went 2-0 with a 3.90 ERA in six games this spring before making his start on Sunday.
"To see him pitch, after what he's gone through," Tulowitzki said, "that's a big accomplishment."
Norris, who led the Astros with 176 strikeouts in 2011, looked just as sharp, fanning five Rockies through the first three innings. He doubled down the left-field line with two outs in the bottom of the third, just his 18th hit in 114 career at-bats.
Norris was stranded when Nicasio struck out Jordan Schafer. Nicasio struck out three through the first three innings, using mostly fastballs.
Jason Giambi drew a walk in the fourth, and one out later, Rosario hit a towering home run to left center. The 23-year-old Rosario, Colorado's youngest position player, hit 40 homers in the minors over the past two seasons.
Houston's starting pitchers went 17 consecutive innings without allowing an earned run before Rosario's two-run shot. But the Rockies mustered only five baserunners the rest of the game and stranded a total of eight.
"We had some opportunity," Tracy said. "It got away from us."
Nicasio also handled the Astros' lineup with ease, making it through seven innings in just 82 pitches.
NOTES: Giambi is tied with Mark McGwire for 38th in major league history with 1,317 walks after three on Sunday. ... The Astros claimed OF Justin Maxwell off waivers from the New York Yankees on Sunday. The Astros will make a corresponding roster move when he reports on Monday.