He played only the last 10 minutes when United beat Arsenal 3-1 in September.

"We beat them without Casemiro - now we have to do the same," said Ten Hag.

United led Palace 1-0 thanks to goal from Bruno Fernandes when Casemiro was cautioned for a late lunge on Eagles forward Wilfried Zaha.

That came eight minutes after they had claims for a penalty when Scott McTominay was challenged by Chris Richards just inside the Palace box.

The visitors' evening got even worse as Michael Olise equalised with a wonderful free-kick in injury time to ensure United, looking to become champions for the first time since 2012-13, dropped two points.

United have lost only once in 20 matches in all competitions and are third in the Premier League - level on points with Manchester City.

Casemiro, 30, has played a vital role in that resurgence since his £70m move from Real Madrid, where he won the Champions League five times.

"He's a really important player for us and a reason we're in this position," said Ten Hag.

"We were winning, controlling the game and an unlucky moment. We have to take that and move on and make the best plan for Arsenal."

United goalkeeper David de Gea made two vital saves to deny Odsonne Edouard and Marc Guehi, but was unable to stop Olise's stunning 25-yard free-kick, which went in off the underside of the crossbar.

"If we want to win in these games, we have to control them until the end," said De Gea. "We dropped two points.

"I was pleased with my save in the first half [tipping Edouard's shot on to the crossbar] but the feeling at the end was not so good because we didn't win.

"It's a big blow to lose Casemiro for Sunday. Now we are missing one of our best players for a big game and it is a big loss for us."