English youth international Harrison, who made one senior appearance for Tottenham Hotspur, notched his first A-League goal in his fifth game and then watched another shot deflect in off Sydney's Paulo Retre for City's second.

City coach Warren Joyce revealed he had given the 21-year-old forward a halftime rocket.

"He had a bit of stick at halftime because I thought Jamie (Maclaren) was doing his work for him and he responded well in the second half," Joyce said.

The result at Leichhardt Oval moved City up a spot to fifth and ended a run of six games without a win, and seven straight losses to Sydney.

The second-placed Sky Blues are nine points behind Perth with five rounds remaining and just a point ahead of third-placed Melbourne Victory.

It was the first time this season Sydney had been held goalless in a league game.

Sydney had the edge in possession and territory, but lacked the guile and precision to pierce a disciplined City defence.

The visitors also created more going forward and after halftime better implemented the press Joyce said they had been working on at training.

"We wanted to be more aggressive in the first half, we wanted to be on the front foot," Joyce said.

"We wanted to be in their faces and catch them and we didn't do it.

"The second half we asked them to do something different, the lads did it and we scored the goals from it as well."

The home team didn't manage a single shot on target for the game, though they had a few attempts from distance.

Harrison, 21, opened the scoring just after the hour when he slotted the ball past Andrew Redmayne after being released by Kearyn Baccus.

Retre had no chance of avoiding Harrison's powerful volley 17 minutes later.

Sydney coach Steve Corica conceded they may have tired following their midweek Champions League game in Japan, having only returned home on Friday.

"We created some half chances, I wouldn't say they were great chances, and I think in games like that you have to take them when they come," Corica said.

"It's been a hard week in Japan travelling back, a heavy field as well and it probably showed late in the second half.

"When the boys started to get a little bit tired they started doing some silly things."

Sydney suffered a blow midway through the first half when centre back Ben Warland limped off the field with a knee injury.

City also lost a defender when skipper Scott Jamieson hobbled off with what looked like a leg problem.

Australian Associated Press