The teenage talent started in their shock 1-0 home defeat to Leganes but was substituted with 15 minutes remaining for Gavi.
Although Yamal was able to walk off the pitch, he will be absent from Barcelona matches until the New Year after sustaining the ankle injury.
"The first team player Lamine Yamal received a blow to the right ankle during the game against CD Leganes on Sunday," the club said.
"Tests carried out on Monday have revealed that the player has a grade one injury to the anterior tibiofibular ligament in the ankle.
"The player is expected to be out for three to four weeks.
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"The Barca winger received a blow to the ankle in the game against Leganes at the Estadi Olimpic Lluis Companys. He lasted until the 75th minute when he was replaced by Gavi."
Yamal, who only recently returned from an ankle injury, has scored five goals in 16 LaLiga appearances this season and leads the assist charts with nine.
The Spaniard has also netted once in the Champions League along with two assists across five outings.
He arrived into the 2024/25 season off the back of a stunning Euro 2024 campaign with Spain.
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Yamal's efforts helped him to be voted as the winner of the Golden Boy award, which is given to the best U21 player in Europe's top tiers.
The winger presented his trophy to fans ahead of kick-off before Barcelona suffered their fourth league defeat of the season.
Hansi Flick's side have won just once in their last six LaLiga matches and therefore been unable to extend their lead at the top.
They may be the league's top scorers on a whopping 50 goals in 18 matches but their 20 conceded is the worst in current the top four.
Atletico Madrid and Real Madrid will overtake Barcelona should they both win their respective games in hand.
Barca have enjoyed much more success in the Champions League though as they sit second behind Liverpool in the league phase.
They have beaten teams including Bayern Munich and Borussia Dortmund to boost their chances of qualifying for the last 16.