Barca, who beat Celtic 7-0 in their opening Group C game, trailed to Thorgan Hazard's opener in Germany.

Substitute Arda Turan fired in the equaliser before Gerard Pique bundled in the winner for the Spanish side.

Elsewhere, Paris St-Germain were 3-1 winners at Ludogorets and Napoli beat Benfica 4-2.

Barca win without Messi

Luis Enrique had to come up with a rare solution to the problem of Lionel Messi's absence, with the Argentine striker missing with a groin injury.

His initial solution was to start Spain international Paco Alcacer in Messi's place, alongside Neymar and Luis Suarez in a front three.

The home side were not overawed, though, and took the game to the visitors, opening the scoring through Hazard's poked finish following Mahmoud Dahoud's pass.

If Enrique's initial tactics were misjudged, he made amends in the second half, sending on Turan, who made an immediate impact with a drilled finish after latching on to Neymar's floated pass over the top.

Pique completed the turnaround nine minutes later, finding the net from close range after Suarez's shot had been blocked.

The 3-3 draw between Celtic and Manchester City means Barca top Group C, two points ahead of Pep Guardiola's side, who they host at the Nou Camp in three weeks.

PSG earn first victory

Like Barcelona, Paris St-Germain got off to a bad start in their away game against Bulgarian side Ludogorets Razgrad with a Natanael curled free-kick giving the home side the lead after 16 minutes.

PSG, who drew their opening game at home against Arsenal, were struggling to get into the game until Marco Verratti unlocked the home defence with a neat pass to set up Blaise Matuidi to level just before the break.

The French side were much better in the second half and claimed victory thanks to an Edinson Cavani double - the first a flicked header from Angel di Maria's free-kick, the second a close-range finish from Lucas' cross.

PSG are level on four points with Arsenal, who were 2-0 winners over Basel on Wednesday.

Napoli take charge of Group B

Arkadiusz Milik scored his third Champions League goal and Dries Mertens hit two as Napoli established themselves as firm favourites to progress to the last 16 with a comfortable victory over Benfica.

Captain Marek Hamsik gave the Italian side the lead in the first half, glancing a header in from a corner.

A three-goal burst in the second half ended the game as a contest as Mertens fired home a free-kick and then finished from close range, either side of Milik's converted penalty for a foul on Jose Callejon by the visiting goalkeeper.

Goncalo Guedes scored a brilliant goal for the Portuguese side before Salvio added a second consolation goal with a neat finish but they were no match for last season's Serie A runners-up.

In Group B's other game, Viktor Tsygankov earned Dynamo Kiev a point at Besiktas, who had taken the lead through Ricardo Quaresma.