Rafinha scored against his old club and Jordi Alba secured Barcelona’s 2-0 victory at Camp Nou, but Inter put in a decent performance.
It's not all bad news, as PSV Eindhoven held Tottenham Hotspur to a 2-2 draw, so they remain comfortably clear in second place.
They were joint leaders of the group going in on a perfect record, but both missed key players. Lionel Messi was out after fracturing a bone in his arm, replaced by ex-Inter men Rafinha and Philippe Coutinho. Samuel Umtiti and Thomas Vermaelen were also sidelined, while the visitors lost Radja Nainggolan, but Marcelo Brozovic and Ivan Perisic shook off knocks.
Mauro Icardi only managed to prod an Ivan Perisic low cross over from six yards under pressure, but Samir Handanovic needed a great reaction save with his legs to keep out Clement Lenglet’s header from a corner.
Icardi went down under pressure from Lenglet as he ran on to a Matias Vecino knock-down, but had slipped when trying to change direction.
Barcelona broke through with a well-worked goal. Luis Suarez put a fantastic cross in off the outside of the boot from the right flank and it surprised Milan Skriniar for the Rafinha cushioned volley from close range. He did not celebrate against the club where he spent six months of last season.
Vecino thumped a ferocious half-volley over the bar, but on the stroke of half-time a Coutinho free kick was deflected inches past the post by Joao Miranda with Handanovic stranded.
Luciano Spalletti introduced Matteo Politano for Antonio Candreva for the second period and it made an immediate difference. Politano’s cross-shot was about to reach Perisic for a tap-in when Marc-Andre Ter Stegen stuck out a hand to palm it off his feet. Moments later, Politano blasted over from the edge of the box after an Icardi back-heel flick.
Suarez rode two tackles to test Handanovic and the goalkeeper was decisive with a reaction block on Lenglet after a poor clearance. There was a curious moment when Suarez tried to fire his free kick under the wall, but Brozovic lay down behind it his teammates to block it off.
Barcelona went on the counter from an Inter corner and Coutinho eventually rattled the frame of the goal with a chest and strike.
Inter substitutes again created a chance, as Kwadwo Asamoah crossed from the left for Lautaro Martinez to fire wide of the near post.
However, Jordi Alba completed two quick give-and-go passes with Arturo Vidal and then Ivan Rakitic to score a very Barcelona-style goal, placing the angled drive across Handanovic.
Barcelona 2-0 Inter
Rafinha 32 (B), Jordi Alba 83 (B)
Barcelona: Ter Stegen; Sergi Roberto, Piqué, Lenglet, Jordi Alba; Rakitic, Busquets, Arthur (Vidal 78); Rafinha (Semedo 72), Suarez, Coutinho (Munir El Haddadi 88)
Inter: Handanovic; D'Ambrosio, Skriniar, Miranda, Asamoah; Vecino, Brozovic; Candreva (Politano 46), Borja Valero (Lautaro Martinez 63), Perisic (Keita 77); Icardi
Ref: Hategan (ROU)