City finished their last match of the regular season with eight players aged 21 or under presenting a monumental selection headache for Joyce heading into the finals.

With the fringe players delivering a hefty home win, City could finish fifth and face Adelaide United away if premiers Perth Glory defeat Wellington Phoenix by two goals on Sunday.

"There’s some good kids chomping at the bit wanting to do well for the football club," Joyce told Fox Sports post match.

A brilliant brace to young Englishman Shayon Harrison (35’, 55’) and goals to Man of the Match Riley McGree (42’), Dario Vidosic (50’) and Ramy Najjarine (90+2’) did the damage against a Mariners outfit that offered little in attack.

It was City’s equal biggest win and one that Joyce said the youngsters had been promising for some time.

“You give players an opportunity tonight to throw their hat in the ring to play in finals football, and they deserve that the way they conduct themselves during the week and the spirit they’ve shown in what’s been a difficult season,” Joyce said.

"Connor Metcalfe has been excellent the last few weeks and was itching for a place but obviously Kearyn Baccus and Luke Brattan have been playing out of their skin and then McGree’s come in.

"You want to give Connor a go …and he’s made his debut tonight.

“Lachy Wales and McGree were outstanding at the start of the season but we’ve lost them to Olyroos... and then it’s hard to integrate them with the new players that come in.

"I think maybe the last 30 minutes at Wellington was the first time some of them have played together…it’s been a bit like that this season."

At 16, Idrus Abdulahi became the youngest player to take to the pitch for the A-League outfit when he was subbed on in the 81st minute. And Joyce was delighted with his cameo: "He put Matty Simon on his backside in a 50/50, drives away with the ball and sets up the last goal."