Huddersfield midfielder Aaron Mooy has been ruled out for up to three weeks due to an injury setback, coach David Wagner has confirmed.

Australia international Mooy, a key performer in the Terriers’ Premier League survival fight, has an infection in the knee he cut in last week’s home win against Bournemouth.

Mooy had returned to his all-action best against Bournemouth after a dip in form in recent weeks, but will now miss Saturday’s FA Cup clash against Manchester United at the John Smith’s Stadium.

“It’s only a cut, but unfortunately there was infection when he got his stitches. This means there is a slight setback, but nothing serious,” Wagner said.

“He will miss the next two games for sure, maybe Tottenham as well, but then he’ll be back, so it isn’t something where ligaments or muscles are damaged.

“It’s only that he got an infection, he’s been unlucky in this situation and will be out for two weeks, maybe three.”

Wagner, as usual, has focused on the positives and said Mooy will now be able to recuperate properly after non-stop football for club and country over the last 18 months.

“I always feel sad if players are injured,” Wagner said. “Especially Aaron, who has played on a very high level against Bournemouth — back to his best.

“It’s very unlucky for him, but he will come back fresh, mentally and physically as well, in two weeks and then he will help us.”

The Terriers, who have not reached the sixth round of the FA Cup since 1972 — the same year they were last relegated from the top flight — secured morale-boosting back-to-back victories last week.

They halted an eight-game winless run by despatching Birmingham 4-1 at St Andrew’s in their fourth-round replay and then registered their first Premier League win since mid-December by out-playing Bournemouth .

“The priority since day one has been the Premier League,” Wagner said. “This doesn’t mean we don’t like to be successful in the other competitions as well.

“We will not worry about this situation. It is our present for our fans that we play Man Utd in the fifth round of the FA Cup at home — the oldest competition in the world.”

Wagner confirmed defenders Chris Lowe and Michael Hefele will miss out due to a hamstring strain and illness respectively, while January signing Alex Pritchard is cup-tied.

But striker Laurent Depoitre, who scored in Town’s 2-1 win against Jose Mourinho’s side in October, will be fit after an ankle injury and midfielder Danny Williams (dead leg) is also back in contention.

“It’s a great occasion, a great situation, a great moment even if we have some injury problems,” Wagner added.

“It’s the cup so we can play this game with all the freedom we have against one of the biggest names in world football at the John Smith’s Stadium.”