http://www.youtube.com/watch?v=lJ-iMBmw6X4
At 0:02 you can easily see what I've been saying every time: defenses don't seem to care much about Tello, and I think that's the reason why he scored yesterday. Everyone is on the left and a few on the middle, while Tello is completely alone. Normally this wouldn't happen, but the defense was scared of Mr Villa as well, which gave Tello that big room to explode. Tello had a good game yesterday, but you can't say he's better than Sanchez just because he scored, because that wasn't because Tello has awesome speed or awesome dribbling skills, it's just because he had the room to do so (which Alexis normally doesn't have because he & Villa don't play together usually).
We'll see how Tello improves in the next weeks. But I really wouldn't judge him that quick or compare him against Sanchez. We still need time to see who's better and why xD