There was the usual strong security presence around the Parc des Princes on Tuesday as Paris Saint-Germain hosted Barcelona in a Champions League showcase against the backdrop of violent unrest across France.

PSG and Barcelona head the standings, though Liverpool or even surprising Stuttgart could end Tuesday on top of the table.

The game in Paris takes place in a very different context to when PSG beat Manchester City 4-2 away last week.

What began in France as protests against school conditions has expanded to include a wide range of other groups and causes. There have been violent clashes, fires and looting.

An emergency meeting with top government officials on Monday confirmed PSG-Barcelona and other soccer matches in European competitions could go ahead after the possibility of calling off games and other big events was discussed.

Dortmund wins early game

Serhou Guirassy scored twice but Borussia Dortmund wasted plenty more chances in a 2-1 win over Azerbaijan's Sabah.

It wasn't the sort of convincing victory the German team was hoping for, after last week saw a loss to Bodø/Glimt before a draw at Union Berlin which allowed Bayern Munich to take the Bundesliga top spot off Dortmund.

Pavel Kacor's leaping volley in the 90th minute earned Slavia Prague a 2-2 draw with Fenerbahce, which had been leading 2-0 early on before a defensive blunder by Mattéo Guendouzi let the Czech side back into the game.

Liverpool could go top with a win over Villarreal if PSG and Barcelona draw, or on goal difference if Andoni Iraola's team can rout its Spanish opposition.

Stuttgart has won both of its games but Atletico Madrid will be sterner opposition for the German team.

City aims to get back on track after last week's PSG loss when it faces Greece's AEK Athens, while troubled Napoli seeks a first point against Norway's Bodø/Glimt.

Also, Roma plays Slovan Bratislava and Porto hosts PSV Eindhoven.