The midfielder turned Tom Cleverley before firing into the top corner from 30 yards.
Sandro's strike put us 2-1 up against the champions but they responded quickly via Wayne Rooney's penalty. That was Rooney's second goal after he levelled Kyle Walker's free-kick blast in the first half.
Sandro is back to his best after spending nine months on the sidelines with a knee injury sustained at QPR in January.
He's now featured in 14 matches in all competitions, starting 10.
"Sandro is one of those players everyone loves, a real character," said Michael.
"Even when he was going through such a hard time on his way back from injury he was still part of it all.
"And what a goal! We've seen that in training a few times."
Michael is well placed to understand what Sandro has been through on his recovery having fought back from serious injury himself in recent years.
"It does affect you, I know that well and I know what it means for him to be back playing again. It’s great to have him back, he’s a great guy."
Andre Villas-Boas added: "It was a great goal. I’m extremely happy for him because he’s been chasing that for quite some time. He scored at Fulham last season and now, a wonder strike."
Kyle Walker is hoping to see more of the same. "We’re all encouraging him to have a few shots at goal. Last season he scored a fantastic goal at Fulham and if he shoots a lot more, we’ll get a few more goals from him."