United face Chelsea in the FA Cup semi-final on Sunday evening as both sides look to finish their season with a piece of silverware to show for their efforts.
“I'm really looking forward to the game," Rudiger told the German FA's official website. “Man Utd are in great form – I mean, they haven't lost in 18 or 19 games.
"They beat us twice in the league, too, so they'll come into it with a huge amount of confidence.
“It's going to be a tough fight, but the good thing for us is that Olivier Giroud is firing again. He struggled for a while and some had already written him off."
Giroud has netted four times in seven matches since the Premier League restarted last month, but is yet to score in the FA Cup this season.