The much-anticipated showdown between the Australian and Japanese champions produced a fizzer with Yokohama 3-0 up by halftime on Wednesday.

Their speed and movement was too much for a Sydney side off the pace after almost three weeks without a game due to a couple of postponements.

Some of the Sky Blues' woes in their ACL opener were self-inflicted, with coach Steve Corica and captain Alex Wilkinson targeting uncharacteristically sloppy defence as well as the layoff as factors in their loss.

"We weren't good enough today no doubt about that," centre back Wilkinson said.

"I think especially in the first half we didn't keep the ball well enough.They pressed really well, we didn' deal with it well enough.

"I thought we were a little bit rusty, not playing a game in three weeks has probably worked against us a little bit.

"But no excuses they were the better team.

"The first goal was a deflection, a bit unlucky and then a couple of others were a bit soft I thought, so we've got to be a bit stronger defensively as well.

"We've got a game on Sunday, so a quick turnaround, forget it and move forward."

Unbeaten in their last 12 A-League games, Sydney have a 10-point-lead at the top of the table and three games in hand over second-placed Melbourne City.

They travel to Gosford to play the last-placed Mariners, who have 27 fewer points and have lost their last five games.

Corica credited Yokohama for playing well, but said a couple of their goals came from Sydney errors.

"They play a very high tempo with the ball, without the ball and that probably surprised us because we haven't played for three week," Corica said.

"We were put under a lot of pressure, we didn't adapt very well to it and the goals that we conceded really were disappointing, they were uncharacteristic for us."

Australian Associated Press