O’Mahony scored Albion’s fourth goal in a 4-0 win over Crawley Town in the second round of the Carabao Cup last night (Tuesday, August 27).
It was a calm finish by the 19-year-old after he dispossessed Josh Flint in front of goal.
It looks set to be his last action for the Seagulls before moving to Championship outfit Portsmouth on a season-long loan.
O’Mahony started the match on the bench but he got his chance a lot earlier than expected after Matt O’Riley hobbled off injured within the opening six minutes.
“He had never played with the team like he did today,” Hurzeler said. “He only played 45 minutes in pre season.
“It’s not so easy to have a game like this and have competition. All our players need a little bit of time, also Mark.
“The longer the game went, the more stable he was, the more actions he had. He’s a great character. He’s a very good guy.
“He always tries to improve. A good scorer in the box. We see that today with his goal. He had two or three more chances.
“In the end, I’m really happy because he’s a young guy. He deserved to score today because he works really hard in training. Now we see what happens.”
O’Mahony made three first team appearances for Brighton under their former boss Roberto De Zerbi and also featured in the pre-season trip to Japan.