Sydney central defender Alex Wilkinson insists the Sky Blues' recent form slum won't dent their belief, but says they have to fix the stupid errors blighting their game.
Virtually unbeatable for most of the past two seasons, Sydney have won just one of their last seven domestic and ACL games and none of their last four.
Their 11-point lead has been slashed to five and Newcastle could close the gap to two if they if they win in Adelaide next Friday.
A 2-0 home defeat by Brisbane on Saturday meant Sydney suffered back-to-back A-League losses for the first time in almost two years.
"I don't think it's going to alter the belief that we've got in the squad," Wilkinson told AAP.
"It''s a squad with a lot of experience, a lot of older heads and a culture that breeds success and winning and that's not going to change because we've had a couple of losses.
"It's not like we're getting cut open every game. It's these stupid errors and silly mistakes that are costing us and making things difficult for ourselves.
"If we fix that we'll be fine, but the belief and the will to win is still going to be very strong within the group."
While Sydney are still proving hard to score against in open play, their recent vulnerability at defending set-pieces recurred, on Saturday.
Brisbane's goals came from a corner and a free-kick.
"It's not good enough, that's three maybe four games in a row now we've conceded from a set-piece," Wilkinson said.
"It's just about concentration, and discipline, get your man and don't let him go."
Wilkinson was denied his first goal in four-and-a-half years and his first in the A-League for seven-and-a-half, when he had a first-half header from a free-kick rubbed out through the VAR for a marginal offside decision.
"I can't do anything about it unfortunately, I don't score too often so it would have been nice,"' he said.
Sydney's next game is away to Central Coast, one of Wilkinson's former clubs and the only A League side Sydney haven't beaten this season.
"We definitely owe them one," Wilkinson said.
Sydney coach Graham Arnold put the onus on himself to lift the club out of the doldrums.
"'We've had two fantastic years of winning and everyone goes through this period and this is the time now where people need to step up," Arnold said.
"I'm the first one to look in the mirror and say 'it's myself,' and drive these boys forward."