Sydney FC had raced into a 3-0 lead at the Sydney Football Stadium and it looked game over with barely half an hour remaining.

However, two goals from Matt Simon and one from Nik Mrdja saw the visitors earn a 3-3 draw.

McKinna said: "The boys believe in each other. I believe in the boys and when you create so many chances goals have to come.

"It was not a fluke [we came back]. We were devastated to be down 2-0 because we dominated most of the first half."

"Like the Adelaide game [the Round 7 comeback for 3-3] we felt as though we could go and get it.

"We were probably a wee disappointed we couldn't have gone and got a winner."

In just 18 minutes, the Mariners turned the game on its head with two goals from Matt Simon and one to substitute Nik Mrdja late in the second stanza.

McKinna heaped praise on his two-goal hero who did not find the net last season.

"This year he's come back from the Olyroos and it's probably given him the confidence to do it at this level," McKinna said of Simon.

"And most defenders in the league hate playing against him because he has an all-action style. And he has got a good touch.

"It's just rewards for a guy who gave up work for nine months to pursue his dream."

The 22-year-old Simon, with seven goals now in the Hyundai A-League, said he's targeted double figures this season.

"Last year I was pretty happy with my season, I just would've liked to have a few more goals or one goal.

"But I always knew I could score goals and the gaffer knew that as well and showed a bit of faith in me.

"And I'm very happy to repay that faith now."