Hansi Flick rested several first-team stars like Dani Olmo, Ferran Torres and Eric Garcia as he wanted to keep them fresh for the Champions League fixture against Paris Saint-Germain next week. Lamine Yamal, on the other hand, returned to the matchday squad from injury but started on the bench.
Barcelona were the more dominant side in the first half as they enjoyed 86 per cent ball possession and created several goalscoring opportunities. Real Sociedad goalkeeper Alex Remiro was the busiest player on the pitch as he pulled off multiple saves to deny players like Pedri and Marcus Rashford from scoring.
After resisting the Barcelona attack for half an hour, the visitors broke the deadlock against the run of play. Goncalo Guedes sent in a curling cross towards Mikel Oyarzabal, who in turn, found Ander Barrenetxea with a pass. The left winger then kept a low ball inside the box from which Alvaro Odriozola converted a simple tap-in.
The Catalan giants restored parity just two minutes before the end of regulation time in the first when Jules Kounde converted a clinical header from Marcus Rashford's inch-perfect corner.
Flick introduced Olmo and Yamal in the second half and the changes instantly had an impact on Barcelona's game. Yamal came on just a minute before the hour mark and contributed to Lewandowski's goal. The youngster received a pass from Olmo near the left edge of the box and made a run before keeping a perfect cross inside the six-yard box as the veteran Polish forward converted a brilliant header. Lewandowski came close to a second goal for himself when Ferran Torres set him up with a perfect ball inside the six-yard box, but the 37-year-old's powerful shot from a close range hit the crossbar and went out.
With a 2-1 win on Sunday, Barcelona overtook rivals Real Madrid to occupy the top spot after Los Blancos suffered a 5-2 loss against Atletico Madrid a day before.