Confident and clinical, Melbourne City have one foot in the A-League Men grand final after claiming a 3-0 win over Western United in the first leg of their semi-final.

But United coach John Aloisi is adamant the ingredients for a fightback are still there.

German Ferreyra gave Aurelio Vidmar's City the lead in the 16th minute before Yonatan Cohen added a wonderful curling second in the 54th at AAMI Park.

A week on from his hat-trick against Adelaide, star United striker Noah Botic started on the bench after suffering a quad injury in the elimination final.

Botic came on in the 72nd minute, mere seconds before Mathew Leckie scored to wrap the game up.

"Three goals puts us in a good position for next week," Vidmar said.

"They had a really good game against us tonight, to be honest, and they probably should have scored.

"We probably scored at the right times. That sort of took a little bit of pressure off us."

City's three-goal buffer leaves Aloisi's United with a mountain to climb in next Saturday's second leg at AAMI Park.

"I've been involved in ... a few games that I've been 3-0 down or 3-0 up at half time and come back and won the game," Aloisi said.

"There was a lot of good to take out of that still, we had our chances. I think we had the same amount of big chances as them, but we didn't take ours and they took theirs.

"So we just have to keep believing and keep on trying to perform like we have been, and if we are able to score a few goals, you never know.

"That's the belief that we have to have."

The winner on aggregate will face either premiers Auckland FC or Melbourne Victory, who play their first leg at the venue on Saturday night.

Friday night's game was played in front of a sparse crowd at AAMI Park, not Ironbark Fields as United have not been cleared to host Melbourne derbies at their smaller Tarneit base.

Hiroshi Ibusuki replaced Botic while City were without Nathaniel Atkinson (calf), with Callum Talbot playing right-back.

"We would have loved to have started Noah, and we would have if it wasn't going to be a risk, but there was a bit of a risk involved, and we didn't want to take that," Aloisi said.

"He didn't want to take that risk either."

City broke through when Marco Tilio curled in a tantalising corner and Ferreyra rose highest to head home off United goalkeeper Matt Sutton.

Tilio could have made it 2-0 in the 36th minute but blazed over the bar, while United's Michael Ruhs shot straight at Patrick Beach two minutes later.

City doubled their lead when Alessandro Lopane worked the ball out to Yonatan Cohen on the right and the left-footed winger curled a wonderful first-time strike into the top corner.

City claimed their third when Tilio launched a cross towards Cohen and the ball ricocheted fortuitously off his hip into the path of Leckie, who steamed in to rifle home his first ALM goal since December 2023.

It was just the 13th appearance of the season for Leckie, who has battled with calf and hamstring injuries.

City's defence held firm late to maintain a three-goal buffer.