He created panic in the Ecuador defence with a well-placed cross that was turned into his own goal by defender Augusto Porozo on 69 minutes.
The goal came only a minute after Diouf could have opened the scoring himself.
He feigned to go outside before cutting back
inside and curled a shot from long-range past Cevallos that
bounced off the post.
After the match Senegal boss Bruno Metsu singled the Lens player out for praise.
"He can make the difference," said Senegal coach Bruno
"The team worked for him and it showed."
Metsu was also happy to have finally achieved a victory in Senegal's warm-up period, which had so far produced poor showings.