Robert Lewandowski headed a second-half winner as Barcelona came from behind to beat Real Sociedad and move top of La Liga.
With the score level at 1-1, manager Hansi Flick introduced Ballon d’Or runner-up Lamine Yamal in the 58th minute.
Within seconds, the 18-year-old dazzled past a defender and delivered a pinpoint cross for Lewandowski to nod home.
Sociedad had stunned the hosts by taking the lead on 31 minutes when Álvaro Odriozola slid in to convert Ander Barrenetxea’s low cross.
But Barca hit back just before the interval, Jules Kounde powering in Marcus Rashford’s corner.
Rashford, on loan from Manchester United, impressed again on the left, forcing two sharp saves from goalkeeper Álex Remiro before being withdrawn on 78 minutes, with Flick mindful of Wednesday’s Champions League clash with Paris St-Germain.
Sociedad nearly snatched an equaliser late on when Takefusa Kubo intercepted Kounde’s lapse but struck the crossbar.
Moments later, Barcelona broke upfield and Lewandowski hit the underside of the bar, with the ball bouncing down on the line but staying out.
The miss proved immaterial as the champions held firm for their sixth win in seven league games, moving one point clear of Real Madrid, who lost 5-2 to Atlético Madrid on Saturday.