Sydney FC say they had no choice but to severe ties with exciting winger Yairo Yau, despite the import disputing reports of his long-term fitness worries.

Sydney FC coach Frank Farina said the A-League club was left with no option but to cut recruit Yairo Yau due to complications with a calf injury.

The Panamanian international has denied reports he is a long-term injury risk, saying he has not received an official diagnosis.

But Farina was clear in his appraisal of the dashing winger’s fitness – saying despite outwardly appearing in good shape, he was unable to complete games due to his calves tightening.

It led to a “mutual termination” of his deal, with five months remaining on the loan.

The final straw came on Boxing Day against Brisbane when the 24-year-old came off the bench as the Sky Blues were trounced 5-2.

“He was physically OK but, 10 minutes into a game, he’d be running and it would tighten up,” Farina said on Thursday.

“The week after (the Brisbane game), he said to me ‘I just couldn’t run after 10 minutes’.

“We thought it was that compartment syndrome … and the doctor confirmed that.

“He was not going to be able to play for us in a busy time, an important time.”

Farina said Yau took the news well and was sympathetic towards Sydney’s needs.

“I had a chat to him and he understood that we needed a player that was going to be ready to play,” he said.

“Unfortunately, he wasn’t going to be ready.”

Yau’s likely replacement on the Sydney roster, Serbian midfielder Milos Dimitrijevic, won’t be available to face cross-town rivals the Western Sydney Wanderers.

But Farina does still expect him to make an impact in the short term, despite not playing regular soccer recently – likening the situation to that of striker Ranko Despotovic.

“He’s obviously a little underdone at the moment and won’t take part on the weekend,” Farina said of Dimitrijevic, who arrived in Sydney on Sunday.

“He’s in pretty good nick. It was similar when Ranko came here as well.

“We saw how he not only adapted but physically was up to it.

“I’m not expecting it will be too long before we see (Dimitrijevic).”

His unavailability does leave some gaps to fill in midfield however.

And with midfield general Nicky Carle suspended and Hagi Gligor out due to Australian under-22s duties, Farina could call on two of the club’s senior members to fill the gaps.

Farina will also be without striker Richie Garcia, who strained his calf against Adelaide last round.

Veteran midfield duo Terry McFlynn and Brett Emerton, as well as young striker Corey Gameiro, are favourites to return to the starting line-up for the grudge match.

“Fortunately, we’ve got the likes of Terry, Brett and Matt Thompson who didn’t start last week,” Farina said.

“It’s still not nice when you lose three or four players from the previous week.”