The 18-year-old forward was absent from the session after suffering from a fever, although the issue is not believed to be serious. The young star had played a key role in Barcelona's recent European fixture against Newcastle United at St James' Park, where he calmly converted a penalty to help his side secure a 1-1 draw in the UEFA Champions League.
According to reports in Spain, Yamal is expected to recover in time for Sunday's league meeting with Sevilla. However, his absence from training highlighted the growing physical strain on Hansi Flick's squad during a demanding run of fixtures.
There was some positive news for the Barcelona manager. Defender Ronald Araujo and midfielder Marc Bernal were both forced off late in the match against Newcastle with muscle complaints, but the club confirmed the problems were only caused by cramp. Neither player is expected to miss any matches.
Meanwhile, Eric Garcia, who sat out the trip to England with muscle discomfort, also avoided a serious injury. The defender trained separately and received physiotherapy treatment after what was described as a minor muscle strain.
Despite those positive updates, Barcelona continue to face a difficult injury situation. Manager Hansi Flick has repeatedly warned about the growing list of unavailable players, which has forced the club to rely more heavily on academy talent.
Youngsters Eder Aller, Tommy Marques, Alvaro Cortes and Xavi Espart were all involved in Thursday's training session. Espart already made his senior debut against Newcastle after Araujo's late injury scare and could feature again in the coming weeks.
Barcelona remain without several key players, including Alejandro Balde, Andreas Christensen, Jules Kounde and Frenkie de Jong. The club are hopeful that Gavi may return in time for Sunday's match.
With defensive options already stretched and several midfielders managing heavy workloads, Flick will be eager to see Yamal recover quickly as Barcelona prepare for another crucial test in their packed schedule.
Xavi Espart was elated to make his debut appearance as a Barcelona player in the Champions League as a late substitute in the Round of 16 match against Newcastle United at St James' Park on Wednesday.
Bayer Leverkusen return to Bundesliga action on Saturday as hosts to leaders Bayern Munich, still grappling with inconsistency that threatens their top-four ambitions.
Liam Rosenior has admitted his side must learn how to handle difficult moments during matches if Chelsea FC are to fulfil their potential, following a damaging 5-2 defeat to Paris Saint-Germain in Paris.
Virgil van Dijk has insisted Liverpool must "fight" and "earn" their place in the next round of the UEFA Champions League after slipping to a narrow defeat against Galatasaray in the first leg of their last-16 tie.
