But as soon the final whistle blew in the 90th minute of Saturday night's 4-0 Union win over Sporting Kansas City, McInerney couldn't help but grin.
"That was one of the best moments of my career," the 19-year-old forward said. "I didn't want it to end."
McInerney jump started a struggling offense with two first-half goals, the first coming just two minutes in, and brought the crowd of 18,207 at PPL Park to their feet for the third time when he exited the game for a substitute in the 72d minute. It was as loud as this stadium has been in an otherwise disappointing season.
The Union (3-8-2) fired the only manager in club history, Peter Nowak, 10 days before Saturday's win. Under Nowak, McInerney sat out six straight games. But when Nowak was shown the door, assistant John Hackworth stepped in in an interim role. That's when McInerney got another chance.
Starting in his second straight game, McInerney banged home two loose balls in the box to catapult the Union. It was the first time in the regular season that the Union scored four goals.
"What a great way for Jack to start the game," Hackworth said. "We were patient and Jack knows how to sniff them out."
The Union added two more tallies in the 80th minute and the 86th minute.
Lionard Pajoy put home a penalty kick in the 80th minute after Antoine Hoppenot was taken down from behind in the box. Pajoy put the PK into the right side of the net to give the Union a 3-0 lead.
Hoppenot sprung free for a breakaway six minutes later and chipped a shot up and over the reach of Sporting Kansas City goalie Jimmy Nielsen for the Union's fourth goal of the night.
The Union had only scored eight goals in the first 12 games of the season. The win was Hackworth's first as manager.
"What a great night for our forwards," Hackworth said. "I hope it's one of many [wins]. I'm not going to get too high or too low."
Zac MacMath posted his third shutout of the season and made a big diving save off a free kick in the 75th minute. Sporting Kansas City threatened shortly after McInerney's first goal, but the Union defense was able to clear out Sporting's set plays.
"Every single guy played well tonight," Freddy Adu said. "That was just a total team effort."
McInerney stepped off the field with 18 minutes still to play. But because of the momentum he started, what was a two-goal lead felt like that twice that. Still, though, even after two goals in the most electric Union game of the season, McInerney refused to smile - for another 18 minutes anyway.
"That was just the best feeling in the world," McInerney said with one last grin.
Contact Chad Graff at 215-854-4550 or firstname.lastname@example.org. Follow him on Twitter @ChadGraff.