AFCON 2021
Hamza Mathlouthi scored with a half-volley in the fourth minute and Wahbi Khazri added a second four minutes later.
Khazri scored his second goal after the break and Seifeddine Jaziri added the fourth.
Tunisia had lost its first match against Mali 1-0 - a game that ended 13 seconds early - but the Tunisians' protests were dismissed by tournament organizers.
Substitute Youssef Msakni, who was making his seventh Nations Cup appearance after recovering from coronavirus, missed a penalty for the 2004 world champions, placing it at the left post.
The Carthage Eagles are only the second team after hosts Cameroon to score four goals in a match at this year's Cup of Nations, and the win leaves them one point behind Gambia and Mali.
Tunisia faces the Gambians in their final group game on Friday (19:00 GMT), while Mauritania is off the pace after two successive defeats to reach the round of 16.
Source: BBC Sports
Tags: MauritaniaTunisiaWhabi Khazri