De Jong was pedestaled as one of the A-League's biggest marquees upon signing for Sydney at the beginning of the season, with the 29-year-old former Newcastle United man set to enter his pomp over the coming few seasons.

Injuries have derailed his campaign, as they did during the Dutchman's stints in the English Premier League and with Ajax. The latest sideline spell the result of a damaging Andrew Durante tackle in Sydney's win against Wellington Phoenix.

The glimpses he has shown, affirmed by a goal-of-the-season contender in Sydney's 3-1 win over Brisbane Roar, have shown him to be one of the league's finest midfielders. 

After the latest performance, Corica's firing off a warning to Sydney's rivals.

“[I’m] pleased for him, he’s worked hard to get back fit,” Corica said.

“He was on a good run before he got injured, scored in his last game and in his first game back he’s scored again which is great and it was a vital goal for us, it made the game done and dusted.

“We’ve still got four games in the A-League plus finals and then Champions League games as well which he’s going to be involved in and we need him match fit."

Sydney are currently six points off Perth Glory and set to face Tony Popovic's league leaders at home on April 18, with Corica hoping the attacking midfielder can not only spearhead Sydney's Championship tilt, but rescue their fading Champions League campaign. 

“We see him at training so we see the best of him," Corica continued.

"You probably haven’t seen the best of Siem yet other than a couple of the fantastic goals he has scored so far but it’s vital for us to keep him fit and everyone else because we haven’t really had that option this year.

"We’ve had three players that have done knees and have been out long term, Benny Warland the latest one.

"I thought he’d been doing a great job when he stepped back in and Danny and Siem as well have been out for long periods of time so we’ve never had the opportunity to have everyone available so it’s good to have that now.”