The winless Wanderers were belted in every department and can count themselves lucky to have not been completely blown away on the scoreboard due to some errant Reds finishing and sterling Ante Covic goalkeeping.
A tough night was always on the cards for the visitors, but their bid was made tougher still when captain Nikolai Topor-Stanley exited the contest in the 17th minute after being booked twice in as many minutes.
Popovic believed his team more than matched Adelaide before being dealt the savage red-card blow.
"In the first 20 minutes they were not better than us," Popovic said.
"For a team away from home, playing a very good side, we showed a lot of confidence and belief ... we started very well.
"But the game changes with that send-off - 70 minutes with 10 men for a team that's playing a third game in a week, it's difficult.
"The boys fought hard; the effort was tremendous.
"I don't think we can fault some of the football we've been playing, especially our last four games at home, and the way we started today was not a team that lacked confidence.
"The reality is it's nine games without a win, but the player's focus has been there."
Popovic admitted Topor-Stanley's 15th-minute chopping of Marcelo Carrusca's ankles deserved a yellow, but the Wanderers boss believes the second booking, for an illegal handball, was unjust.
"I really didn't think that was a yellow," Popovic said.
"I thought he actually got pushed.
"That was watching it live. I'll need to have another look at it.
"I might change my mind once I've seen it (replay)."
For Popovic and his men, the focus now switches the World Club Cup, starting with a clash against Mexico's Cruz Azul next Saturday, with the winner to tackle powerhouse Real Madrid in the next round.
Popovic says his players should be rightly proud and he wants them to enjoy the moment.
"We've got to go now to Morocco which we should be proud of and look forward to," he said.
"You're representing Australian football, you're representing the Wanderers and and we want to do Australian football proud.
"When we get back we've got a big job ahead of us in the A-League but we've got to enjoy this over there.
"I can guarantee you once they get to Morocco and the reason why they're there is because they're the Asian champions, we'll enjoy our week and do everything we can to set up a magical date against Real Madrid."
