Rangers boss Redknapp admitted he was "surprised" he was able to prise Sandro away from White Hart Lane ahead of the September 1 transfer deadline.
Sandro joined QPR in a £10million deal - but Redknapp said Spurs had rejected "four or five million more" from Russian club Zenit St Petersburg.
"I was surprised we were able to get him to be honest, and that he wasn't playing more," said Redknapp.
"I think Tottenham turned down a big bid from Zenit just before the start of the season.
"It was certainly four or five million more than we paid for him.
"So I couldn't be more pleased to have him, he's a great character, a good lad and I think he'll be a great player for QPR."
Former Tottenham boss Redknapp remains delighted to be reunited with Sandro, but conceded the 25-year-old still needs time to reach full match fitness.
"I don't know long he'll need to be up to full speed," said Redknapp.
"But he hadn't played at all and there's nothing like matches, until you get on the pitch you can't bring it all together.
"It's taking on the nerves, the adrenaline, all the training in the world doesn't compensate for playing in 90-minute games, and that's what several of them lacked.
"Sandro will be fitter on Saturday than he was last week and he's going to be a great player for us."
Source : PA
Source: PA