The 23-year-old Brazil international was substituted after 25 minutes at Loftus Road, having gone down clutching his right knee as he reached for the ball.
A statement on www.tottenhamhotspur.com read: "Sandro has undergone knee surgery following the injury that forced his substitution against QPR at the weekend. The midfielder's recovery schedule will be assessed over the next few days."
Sandro took to his Twitter account soon after Spurs announced news of his surgery, posting a picture of himself being treated on the pitch along with the message: "Sorry guys, but this one really got me, the beast is hurt..."
He also tweeted soon after the game on Saturday, telling his followers: "Hi guys, I'm in some pain at the moment! On my way to the hospital for a scan now so fingers crossed it's good news...thanks for all support."
Sandro joined Tottenham in July 2010 from Internacional and has established himself as a fans' favourite at White Hart Lane.
The all-action midfielder made 25 appearances in his first season with the club and 27 in the second, scoring one goal in each and particularly impressing in the 2010/11 Champions League campaign.
He has also won 16 caps for Brazil, helping the Selecao to a silver medal at last summer's London Olympics.
Source: PA
Source: PA