The 21-year-old's career stalled last season following his £15m move to Manchester United from the Eagles as he struggled to earn regular playing time, and he has now rejoined Palace in a loan move until the end of the campaign.
Warnock feels that if the winger can find his form in the Premier League, he has the ability to become a top player for club and country.
"I don't think his career is in jeopardy," Warnock told reporters. "I wouldn't say we need to save his career, we just need to get games under his belt now and he needs to put himself back in the shop window [for England].
"To do that he has got to consistently be good, week in, week out. That has to be his aim this season.
"The problem has been he has not had enough games. He needs games, last week he ran out of steam a little bit but he is putting the work in on the training ground. Ability and confidence is nothing he has ever been missing."
Palace take on Everton in their Premier League clash later today.