Michael Carrick had combined with Shinji Kagawa to unlock the visitors’ defence and give the Red Devils a seventh-minute lead in their opening Champions League Group H game.
With Galatasaray threatening, the 19-time English champions were presented with an opportunity to seal three points when Rafael was fouled by Burak Yilmaz in the box in the 53rd minute.
But Nani’s weak attempt was easily saved by Fernando Muslera, amounting to United’s third spot-kick miss of the season – Van Persie and Javier Hernández have both spurned penalties in the Premier League.
“Maybe the confusion arose from the fact that Chicharito took it on Saturday when Robin wasn’t available and today Nani grabbed the ball because he wanted to take it,” Ferguson told United’s website.
“Robin van Persie, to me, takes great penalty kicks. I don’t see why he shouldn’t take them.”
The 70-year-old was delighted to see Darren Fletcher make his return from an extended break due to ulcerative colitis against the Turkish outfit, with the Scotland international coming on as a 79th-minute substitute.
“He’s been out for a long time and I think the supporters recognise what a difficult time the lad’s had,” said Ferguson.
“That [the crowd’s ovation] was a mark of respect to a really honest and tremendous young lad.
“I was pleased for him. He didn’t do great but he didn’t do badly. Taking into consideration it was his first game for ten months, I think he acquitted himself very well.”