Lionel Messi became the first player to score in 15 consecutive Champions League seasons as Barcelona claimed a narrow win at Slavia Prague.
Captain Messi gave Barca an early lead with a first-time finish after an exchange of passes with Arthur.
The Czech champions were deservedly level when Jan Boril poked home Lukas Masopust's pass from 16 yards.
But Messi's free-kick found Luis Suarez at the back post - and his cross-shot hit went in off Peter Olayinka.
Barcelona, who are top of La Liga, have now won six consecutive games in all competitions.
The result keeps Ernesto Valverde's side top of Group F on seven points from three games, three points above Inter Milan and Borussia Dortmund.
Those two sides met at the San Siro in the group's other game, with Inter winning 2-0. Lautaro Martinez scored and had a penalty saved before Antonio Candreva's late clinching goal.
Alex Oxlade-Chamberlain scored twice, including a stunning outside-of-the-boot finish, as Champions League holders Liverpool hammered Genk in Belgium.
The Reds' 100% winning start to the Premier League ended with a draw at Manchester United on Sunday, but they returned to winning ways by showing their class in the Group E match.
England international Oxlade-Chamberlain, who missed almost all of last season with a knee injury, drilled in a low shot in the second minute and brilliantly converted a second with a cool, first-time finish from Roberto Firmino's pass.
Sadio Mane dinked in the third from Mohamed Salah's through ball and the Egyptian turned past a defender and rolled home the fourth late on.
In other games, Chelsea won at Ajax, Leipzig beat Zenit 2-1 Napoli secured a 3-2 away victory against Salzburg, Lille drew 1-1 with Valencia and Benfica beat Lyon 2-1 at home.