Luka Jovic said he is ready to answer the call at Real Madrid following a slow start to life in the Spanish capital.
Jovic – who scored 27 goals last season – is still settling in after joining Madrid from Bundesliga outfit Eintracht Frankfurt in a reported €70 million (£62m/$79m).
Jovic, though, did help set up a goal with a stunning flick in his first La Liga start as Madrid drew 2-2 at Villarreal prior to the international break.
Asked about his start to the season with Madrid, the 21-year-old admitted to reporters that his transition has been tough, but that he’s ready to step up when called upon.
"After the pre-season, of course it's getting better now,” he said.
"I was injured, it was that red card when I had to come off against Arsenal [in the first half of the International Champions Cup clash after Nacho Fernandez was sent off].
"It's not easy for one young player, but I think I handled it in the best way possible and I'm ready to answer the biggest demands."
Serbia play host to Portugal and Cristiano Ronaldo, with the Balkan nation third in Group B, six points behind leaders Ukraine and two clear of Saturday's visitors.
There will also be a new head coach on the sidelines after Ljubisa Tumbakovic replaced Mladen Krstajic, who was sacked after June's 4-1 rout of Lithuania following their 5-0 humiliation against Ukraine.
And the forward says his side will be ready to deal with Ronaldo, but that there is more to Portugal than just the former Madrid and current Juventus ace.
"As far as I know, we play 11 on 11, we don't just play against Ronaldo," Jovic said. "We will prepare for the whole team, not just Ronaldo.
"He is certainly their best individual, but they have many more interesting players who can make a problem. It will be necessary to be concentrated and disciplined as much as possible to achieve a positive result."