I thought Sa made a couple of bad errors yesterday, he left a huge gap to his right for Mane to slot into, Mane muffed his shot, but there was still plenty of space for it to go into.
There was also a through ball that ended up deep into his 6 yard box, i have absolutely no idea why he didn't come for that, especially as he is usually so assertive in those situations, the ball was then played through his legs, they should have scored.
Also, and this is less of an error, but i thought it was a penalty when he came out and challenged Mane, but Mane was half a yard offside anyway, not that Sky bothered to mention that.
It's possible that the knock he got came from the penalty incident.