Melbourne Victory captain Kevin Muscat has labelled his side's midweek A-League loss to Wellington Phoenix unacceptable, but says they must quickly move on.The Victory, who play second-placed Adelaide United on Sunday, had a four-match winning streak snapped with a 2-0 loss to the Phoenix in Wellington on Wednesday night.Muscat, who was rested from the clash in a pre-planned move due to a heavy schedule of matches, said the result flattered his side, who were comprehensively outplayed.The defence struggled without their 37-year-old skipper, although the Victory, also missing star strikers Archie Thompson and Robbie Kruse, were down in all areas."The result was disappointing, but I think the performance was even more disappointing," Muscat said on Thursday.The veteran, who did not fly to Wellington with the team, said he had benefited from the break, but the team had not."That was something in the pipeline many weeks ago, not to travel across to Wellington, I'm disappointed (with the performance)," he said."The body's great, I'm feeling really good, I'm looking forward to the run home now with a little bit of confidence, albeit last night's performance was not acceptable."Muscat said while Melbourne could not afford to repeat that form, their focus needed to quickly shift to Adelaide at AAMI Park on Sunday.That change of mindset should be helped by the two clubs' strong rivalry and Victory's eagerness to continue building on a 10-match winning streak against the Reds."The momentum before (the Wellington loss) was great, seven matches on the bounce without a loss," Muscat said."No doubt the boys will be hurting ... but we've got an important game here in Melbourne on Sunday afternoon, so there's not much time to sit around and dwell over it."We've got to pick ourselves up and prepare for an important game."