Oleksandr Zinchenko expects "true warrior" Gabriel Jesus to return "much strong than before" after his injury but has backed Eddie Nketiah to step up for Arsenal in the meantime.
Mikel Arteta's side will resume their Premier League campaign five points clear of Manchester City at the top of the table after impressing before the World Cup break.
Arsenal host West Ham on Monday, but they will do so without Jesus after the Brazil forward underwent knee surgery following an injury in Qatar.
Zinchenko, who joined Arsenal with Jesus from Manchester City in the last transfer window, vowed his team-mate will return stronger as he encouraged the Gunners to step up in his absence.
"He's one of the leaders in our team. He's a true warrior," the Ukraine international told the club's official website.
"I have no doubts he'll be back much stronger than before, knowing him personally and knowing his character. As a team, we need to stick together."
Nketiah is likely to lead the line in Jesus' absence after largely playing a back-up role within Arteta's squad.
The 23-year-old scored five goals in the final seven league games of last season, though, and Zinchenko believes he will prove a capable replacement.
"I have no doubts that Nketiah is going to do his job amazingly, and everyone trusts him," the defender added. "We have such a great group of people. We have this feeling of togetherness."
Zinchenko is no stranger to pressure after winning four Premier League titles with City, and he insists Arsenal will not run out of steam this season.
"I'm just trying to do my job as well as I can. On the pitch, I am giving my 100 per cent," he continued.
"The fans have welcomed me so warmly at this club. I can't be grateful enough for everything they have done and the support I've received from them.
"What I've seen in the past [is] if you have the right attitude and the right behaviour on and off the pitch, you can't be tired physically. You can be only tired in the head – everything is coming from your head.
"If you do all the things right in your routine – your sleep, your food, look after yourself well – and you do everything to prepare your body fresh, if you do everything right, you can't be tired physically."