Kylian Mbappe scored two penalties as 10-man Real Madrid battled to victory over Marseille in their Champions League opener.

Los Blancos were handed an early blow when Trent Alexander-Arnold pulled up with what appeared to be a hamstring injury after only three minutes.

And they suffered another setback when the England full-back's replacement, Dani Carvajal, was sent off with 18 minutes left after he faced off with Geronimo Rulli and moved his head towards the Marseille goalkeeper.

But the 15-time European champions emerged victorious thanks to Mbappe, who twice stepped up to slam spot-kicks past Rulli, taking his club tally to six in five games this season.

Timothy Weah had opened the scoring for Marseille in the 22nd minute, beating Thibaut Courtois with a powerful strike after former Manchester United forward Mason Greenwood stole possession from Arda Guler in the middle of the pitch.

But their lead lasted just six minutes as Mbappe, who had come close to scoring in the early stages with an acrobatic bicycle kick, converted his first penalty after Geoffrey Kondogbia had brought down Rodrygo in the box.

Pierre-Emerick Aubameyang twice came close to restoring the French side's lead, but dragged the first effort wide, before Courtois punched away the ex-Arsenal captain's second strike.

Even after Carvajal's red card, Real continued to create chances and were rewarded for their efforts when visiting defender Facundo Medina handled following a strong challenge to stop Vinicius Jr in the box.

Once again, Mbappe kept his cool and his penalty had enough pace to beat Rulli, who had guessed the right way.

Real are looking to reclaim their crown, having failed to defend their title last season after falling to Arsenal in the quarter-finals.

Xabi Alonso, in his first season in charge, will also be keen for the club to better last term's league phase, where Real finished 11th and needed to go through the play-offs to reach the knockout stages.

The La Liga leaders travel to Kazakhstan to face Kairat on 30 September in their next Champions League game, while Marseille host Ajax on the same night.

It was a disappointing early end to Alexander-Arnold's first Champions League game for Real Madrid.

The 26-year-old, who left his boyhood club Liverpool at the end of last season, had been given the nod to start at right-back ahead of Carvajal.

But he pulled up while running for the ball and immediately held his hamstring before being replaced by Spain international Carvajal in the fifth minute.

Depending on the severity of the injury, the England full-back could miss out on a return to Anfield, with Real Madrid due to visit Liverpool in the Champions League on Tuesday, 4 November.

It was another blow for Alexander-Arnold, who had started just two of Los Blancos' four La Liga games this season and was left out of Thomas Tuchel's squad for the September World Cup qualifiers against Andorra and Serbia.