The 33-year-old ex-Arsenal striker joined Chelsea in a £10million deadline-day deal from Barcelona, but has had to cope with a broken jaw suffered during a home invasion.
The Gabon striker had a custom-made mask fitted by specialists in Italy, and trained fully with Chelsea on Sunday.
Croatia midfielder Kovacic will be filled with pride to go up against his first and home club on Tuesday, but also hopes to see Aubameyang flourish in Chelsea blue.
"I can say he will be a big addition to us," said Kovacic. "He's a proper striker, a goalscorer, which we have missed.
"In the last years we haven't had a 20, 25-goal striker that you need to win the title. So we're looking forward to having him in our squad.
"He's a proven goalscorer. It's normal for him to score goals and I hope he will do it here at Chelsea also."
Aubameyang might have to wear a protective face covering in Croatia, but the forward is no stranger to masks of a different kind.
The Marvel fan has celebrated goals at both Dortmund and Arsenal by donning superhero masks, including Spiderman and Black Panther.
Aubameyang has previously explained how he started the celebration routine to make both his son and other young football fans happy.
Chelsea boss Thomas Tuchel laughed off the mask link, but admitted he will be happy for Aubameyang to celebrate however he likes - just as long as he scores.
"Don't put any ideas into Auba's head please," joked Tuchel. "Not any further ideas anyway! I'm pretty sure he has his own ones. When he scores he can celebrate, but first of all he needs to score.
"He's very ambitious, focused, hungry to play for us, hungry to prove a point, still. That's why he's here and that's why he plays for us. So we're happy for him to prove a point tomorrow.
"Auba trained on Sunday with his mask and had a test and felt fine. There were no issues yesterday when he trained and I hope there will not be today.
"If an issue were to come up we would not put him in of course. I think he could maybe start, but I think he cannot play 90 minutes. So it's on us to take a decision to manage his minutes.
"It's clear though that he needs minutes to find full match fitness and rhythm."
Juventus loan recruit Denis Zakaria has also travelled to Croatia and could be another to make his Chelsea debut, with the Swiss midfielder's work permit having been obtained.
Thiago Silva has not travelled with Chelsea opting to rest the 37-year-old Brazil defender.
Edouard Mendy is fit, having shaken off any issues from Saturday's challenge with Jarrod Bowen in Chelsea's 2-1 win over West Ham.
Hammers boss David Moyes accused Mendy of faking injury after Maxwell Cornet's goal was chalked off after VAR review, denying West Ham a 2-2 draw.
Moyes has avoided punishment from officials despite confronting referee Andy Madley and branding VAR official Jarred Gillet unfit for duty.
Tuchel refused to be drawn on the wider fallout from Saturday's win, off the back of his combined £55,000 in fines from Chelsea's 2-2 draw with Tottenham.
Asked to respond to Moyes' criticism of Mendy, Tuchel replied: "I did not feel anything. I did not hear the accusations. Mendy is available for tomorrow.
"You know what happened to me when I spoke about the referee, and it was pretty expensive. I told you I would not comment any more.
"Also I don't respond to David, I can understand his frustration, his point of view. And we'll leave it there."
Asked for his general view on the current state of officiating, Tuchel added: "What can I say now to be clear at the same time and not pay a fine again?
"Where is the line? Maybe it's better for someone else to comment now."