Ronald Koeman has defended Matthijs de Ligt but says the Netherlands centre-back must alter his game at Juventus.
The former Ajax captain has made a stuttering start to the 2019-20 season for both club and country after joining the Serie A champions.
De Ligt was at fault as Northern Ireland opened the scoring against Netherlands on Thursday, Josh Magennis beating him in the air.
It was the latest in a series of errors the 20-year-old defender has made this term, but Koeman backed De Ligt to come good.
"It is clear that he has to make a change in the way he plays at his club," Koeman told reporters.
"That can sometimes be at the expense of the confidence of a player, but Matthijs gets full confidence from us, and I am sure that in the end he will only get better."
Netherlands will be without Memphis Depay when they face Belarus on Sunday, the forward having scored twice in the comeback win over Northern Ireland.
"It was too great a risk to let him play," said Koeman of Depay, who has dropped out of the squad due to a thigh issue.
"Of course it is a shame, you always miss players like this, but luckily we have more good attackers.
"We had already made the decision to select an additional attacker. We are playing with three attackers tomorrow, and we have three behind them. That seems enough to me."
The state of the pitch in Minsk has made headlines but Koeman is unconcerned about the Dinamo Stadion surface.
"I took a look at it, but it didn't even bother me that much," he added. "It didn't matter that much that we now train on a side field."