"I was like, 'OK, here we go,'" he said.
The laid-back McHugh delivered one of the Astros' best pitching performances in recent memory, striking out 12 batters and allowing only three hits and no walks in 6 2/3 scoreless innings to get his first Major League win in a 5-2 victory over the reeling Mariners.
McHugh, called up after ace Scott Feldman was placed on the disabled list Monday, became the first Astros pitcher to record 12 strikeouts with no walks or runs allowed since Randy Johnson in 1998. It was the most strikeouts in an Astros debut since J.R. Richard fanned 15 in 1971.
Not bad for a guy who entered the game with 13 Major League strikeouts in 47 1/3 career innings. He was 0-8 with an 8.94 ERA in 15 career games (nine starts) prior to Tuesday.
"It was good to get the proverbial gorilla off your back with a 'W,'" McHugh said. "[Catcher Jason] Castro had a great game plan coming in. Between him and the coaching staff, they did a real good job of preparing me. I didn't know a lot of these guys in the lineup, so I was going to go with him, whatever he had. We were fortunate enough to execute pretty well and play some great defense, and getting some early offense really takes the pressure off."
The Astros led, 4-0, in the seventh on the strength of three homers and tied a season high with 10 hits. Castro went to the opposite field with a two-run shot in the first inning, Chris Carter blasted a solo homer in the second -- his first of the year -- and Matt Dominguez homered for the second game in a row in the seventh.
Anthony Bass and Josh Fields combined to close out the Mariners with 2 1/3 scoreless innings, with Fields getting his second save. The Astros took the series from Seattle and won consecutive games for the first time since starting the year 2-0.
McHugh, claimed off waivers from the Rockies in December, was pulled with two outs in the seventh inning after throwing 89 pitches, which were 16 more than he had thrown in any of his four outings this year for Oklahoma City.
"You want to be mindful and know that it's just one start and he's going to have to make more starts and you don't want to have to push him too far," Astros manager Bo Porter said. "We pushed him to a good point. He felt fine and he did a tremendous job for us."
When McHugh arrived at the clubhouse on Tuesday, he and Castro had a crash course on how to pitch against the Mariners. That was challenging because he hadn't faced most of the hitters, and Castro had only caught him a little bit during Spring Training.
"It's a little difficult because you don't really know and don't have a feel of what he has been doing, what's been working for him," Castro said. "You have a short amount of time to get on the same page. I think I only caught him once or twice in Spring Training. I was familiar with the type of stuff he had, but tonight everything was clicking and he was firing on all cylinders. It was a fun game to catch."
The plan was to pitch up in the zone more to change eye levels and establish the inner-half of the plate with his 94 mph fastball and cutter, Castro said.
"It was a little different than the scouting report we got," Mariners manager Lloyd McClendon said. "He was throwing 94 with a pretty good cut slider or cut fastball in. He commanded the strike zone pretty good. He was exceptional tonight."
The strikeouts came as a surprise to pretty much everyone.
"I don't think anybody prepares to go out and strike out a bunch of people," McHugh said. "I knew that I had pretty decent command with two or three pitches, and any time you can go out there and compete with some of your off-speed pitches as well, you have a pretty good chance to be successful."
Veteran left-hander Raul Valdes replaced McHugh in the seventh and promptly walked Kyle Seager before giving up a homer to Justin Smoak that cut the Astros' lead to 4-2. The Astros finally strung some hits together in the seventh getting singles by Castro, Jesus Guzman and Alex Presley to load the bases with one out for Carter, who stroked an RBI single to center to put the Astros ahead, 5-2.
"Smoak hit the two-run home run and they were down two and had the momentum, and I think us getting that run late in the game was big for our team and the momentum," Carter said.
McHugh, 26, was drafted by the Mets in the 18th round in 2008 and had pitched 15 games in the Majors during the last two years with the Mets and the Rockies. Needless to say, it was a long road to his first Major League win.
"I've had a lot of people encouraging me the last few years, just kind of bouncing around a little bit and not really knowing where home is going to be," he said. "For my wife, who couldn't be here tonight, and my family back in Atlanta, this is kind of for them."