If the deal comes off, Newcastle will pay £2 million in a loan fee and the entirety of his £100,000-a-week salary until the end of the season, The Mail claims.
But considering the Spanish striker hasn't exactly set the Premier League alight following his £5.2 million summer move to Everton from Malaga, is Benitez taking a big risk?
The former Barcelona product hasn't kicked a ball for the Toffees in 2018 and has only managed eight Premier League appearances, not scoring in any.
And Newcastle are hardly in a financial position to start handing £100k-a-week deals to players who, simply put, have done absolutely nothing to warrant that salary in England.
Times are tough on Tyneside and cash-strapped United don't have the luxury of paying Sandro £1.6 million in wages until June and another £2 million to Everton for the loan.
Maybe Benitez could justify it if Sandro had shown the potential of being a hit in the England's top flight, but he hasn't. There is very little evidence that he has what it takes to be successful in the Premier League and the Spanish manager would and could look very foolish if he wastes £3.6 million on a striker who doesn't score goals in the North-East.
There would be nowhere to hide for him. Fans can blame owner Mike Ashley for the fact that Benitez has very little money, but they can't blame Ashley if Benitez stakes a big chunk of his limited budget on a gamble which in all probability will not pay off.
Given that Benitez's side are only a point above the relegation zone, there is simply no margin for error here. If he signs a striker then he has to get it spot-on and Sandro, without a single Premier League goal to his name, can't be the best option available for whatever money he has.