Barcelona made it eight wins in a row in all competitions as they picked up their second win in the Champions League this season, beating Sporting Club 1-0 in Lisbon.
However, Ernesto Valverde's side were not at their best and relied on an own goal from Sebastian Coates to win the game.
Valverde picked his strongest available side, with Sergi Roberto taking the place of the injured Ousmane Dembele on the right -- Gerard Deulofeu wasn't even in the squad.
There were few early chances. Luis Suarez curled over from 20 yards and Bruno Fernandes forced Marc-Andre ter Stegen into a routine save.
Barca had a lot of possession but were unable to penetrate in the final third.
Lionel Messi's best chance of a quiet first half came when he wriggled into the box, but his right-footed shot was blocked by former Real Madrid man Fabio Coentrao.
Moments before, Barca's best chance had fallen to Suarez, who fired wide from close range after good work from Messi and Jordi Alba.
A comical moment ocurred before the break, when Seydou Doumbia was taken off injured after being adjudged to have dived, earning himself a yellow card, too.
The breakthrough eventually came early in the second half. Messi's free-kick was flicked on and, under pressure from Suarez, the ball hit Coates and bounced past Rui Patricio.
Sporting pressed for an equaliser but Ter Stegen was in good form, making a second, more impressive save from Bruno.
Barça had chances to make it 2-0, too. Messi was denied by a brilliant block from Jeremy Mathieu, while Paulinho's shot was blocked by Patricio when Ivan Rakitic put him clean through.
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Valverde's side extended their impressive start to the season, though, and now lead Group D by three points ahead of October's game against Olympiakos.