In an intriguing twist ahead of Saturday's season-opening derby, Sydney chief executive Mark Aubrey revealed that the Sky Blues opted against making a move for Mata as they finalised the capture of their own marquee signing in Brazilian winger Douglas Costa.
There is a world where Costa and Spanish international Mata could have been teammates.
But around the same time Mata was brought to Aubrey's attention, the Sky Blues had already signed exciting German-Moroccan playmaker Anas Ouahim.
"We had some conversations with Juan Mata and we did get offered a lot of other players," Aubrey told AAP.
"Juan Mata is obviously a class player and we're stoked he's in the A-League because I think it's good for the A-League in general and for our rivalry.
"But by the time we had a conversation with Juan Mata we already had Anas in that No.10 spot and he's proving to be a real star … we didn't really have a spot for Juan in the team because we didn't need another No.10.
"With limited spots and Douglas on the radar we couldn't make Juan Mata work but as I say, I'm delighted that he's in the A-League."
Douglas Costa poses for a photo at the venue for Sydney's opening ALM clash against the Wanderers. (Dan Himbrechts/AAP PHOTOS)
There is hope that the duo's arrival will give a much-needed boost to a league that has failed to match the interest seen during the days when Alessandro Del Piero and Shinji Ono straddled the divide between the two clubs.
"There is only one Ale Del Piero and I could never compare to him," Costa said.
"He was my idol when I was at Juventus … if he wants to come back I'd like to play with him."
Costa has been stopped for selfies all across Sydney and the club is already seeing a boom in interest since landing the former Bayern Munich man.
Costa's signing video reached nearly one million viewers on Instagram and the Brazilian accounts for a third of their jersey sales.
"I've met a lot of Brazilians here so I don't have to explain why I'm here, they know me already," Costa said.
The Wanderers said Mata's arrival had boosted memberships by 15 per cent and the former Manchester United and Chelsea midfielder doesn't hesitate to explain where he's had his strangest fan interaction.
"A restaurant toilet," Mata laughed.
"A lot of people follow the Premier League so I've felt appreciation from people in the streets.
"I'm used to it but I'm grateful for it, I think that's one of the greatest things of my career."
Wester Sydney's Spanish import Juan Mata enjoys a moment during his press conference. (Dan Himbrechts/AAP PHOTOS)
In recent years big-name ALM recruits such as Daniel Sturridge and Nani have failed to match the hype.
Costa, 34, has looked promising in Sydney colours in the Asian Champions League 2 but the jury is out on the 36-year-old Mata, who hasn't got through a 90-minute performance in close to two years.
"I feel good and ready to go but of course it's up to the coach," Mata said.
"I don't think any team will be at 100 per cent but we are physically ready and most importantly we are mentally ready for the season ahead … Hopefully this can be a good derby for us."
