After an impressive start to his career at Old Trafford, Di Maria's form has dipped in recent weeks, leading to criticism from some quarters.
However, Giggs believes the Argentinian will prove his doubters wrong and return to putting in match-winning displays.
"I think his confidence is fine," he said. "He's a quality player and we'll be looking for him to produce because it is big game after big game now.
"Players get used to different leagues, sometimes quickly and sometimes it takes a bit of time.
"He had a really good start to the season, but with players who take risks and who can win games, it's always difficult to be consistent because they will try things that other players won't do.
"They're capable of doing that and that's why they're match-winners and the best players."
