The Dane has battled for form since his January arrival from Tottenham.
"When I came to Ajax in 2013, he went to Tottenham shortly afterwards," Krkic told La Gazzetta dello Sport.
"In the Premier League, when I was at Stoke, I played against him a lot of times. We are talking about a brilliant talent. It's not easy in Italy, so you have to have some patience with him.
"I'm sure he's going to do well."