The veteran striker slotted home from the spot in the 10th minute to fire the Catalans ahead and reach his milestone, adding a second late on after Dani Olmo's goal to inflict the French side's first defeat.

After dropping points in their last two outings in La Liga, coach Hansi Flick had urged his players to "eliminate" mistakes in their game and Barca produced a solid display.

They got off the mark quickly when Brest goalkeeper Marco Bizot clumsily clattered into the back of Lewandowski after the forward controlled Pedri's cross on his chest.

The striker dusted himself down and dispatched the penalty clinically to open the scoring after 10 minutes and bring up his century.

It made Lewandowski only the third player to reach that milestone in the competition, behind former Barcelona great Lionel Messi, on 129, and former Real Madrid star Cristiano Ronaldo, with 140.

Under Flick, the forward's form has improved significantly this season, reaching 22 goals in 19 appearances between La Liga and the Champions League.

The 36-year-old has made 125 Champions League appearances with Barcelona and before that German sides Borussia Dortmund and Bayern Munich.

"I am very happy, many years ago I did not think I could score more than 100 goals in the Champions League," Lewandowski told Movistar.

"For me the most important thing is that we try to win every game, if I can score, then that's the perfect solution.

"I don't know how many games we have left before the end of the year but we have to win them all and rest over Christmas."

Barcelona were still without teenage star Lamine Yamal, recovering from an ankle problem, but Raphinha was busy on the right and the Catalans dominated proceedings.

They did not create many clear chances though until Fermin Lopez forced a fine save from Bizot with a diving header.

The Dutch goalkeeper made amends for his earlier mistake by denying the Spaniard with his leg.

Olmo on target

Lopez again came close early in the second half when Lewandowski put him in with a neat flick but Bizot was alert to save his low effort.

Playmaker Olmo had an effort scrambled off the line by Brendan Chardonnet as Barcelona sought to put the game to bed.

The former RB Leipzig midfielder eventually grabbed the second in the 66th minute when he received Gerard Martin's pass in the box, showing some nifty footwork to dodge Chardonnet and beat Bizot at the near post.

Brest thumped RB Salzburg 4-0 and had dropped just two points from their first four matches despite sitting in mid-table in Ligue 1, but were brought down to earth at the Olympic Stadium.

Mathias Pereira Lage drilled home to momentarily delight nearly 3,000 travelling supporters but their joy was curtailed when the linesman raised his flag for offside.

Barca substitute Pablo Torre should have netted Barcelona's third when he intercepted a pass with just the goalkeeper to beat, but fired wide.

Instead the job fell to Lewandowski and he rolled home his 101st Champions League goal with aplomb, beyond Bizot's outstretched arm.

Brest fall a few places down the table but their strong start to the campaign means they are well placed to secure at least a play-off spot, while Barcelona are aiming to reach the last 16 directly.

Flick's side travel to last season's runners-up Borussia Dortmund next, before visiting Benfica and hosting Atalanta.