Havertz headed Arsenal into the lead and Saka netted before the interval to underline their superiority at the Emirates Stadium.

After drawing their opening league phase tie at Atalanta, Mikel Arteta's side moved onto four points in their bid to reach the knockout stage of the revamped tournament.

Eliminated by Bayern Munich in the Champions League quarter-finals last season and pipped to the English title by Manchester City, the Gunners are now unbeaten in nine games in all competitions this term as they chase silverware on both fronts.

There was further good news for Arsenal as Spain midfielder Mikel Merino made his long-awaited debut for the last 30 minutes.

Merino's recovery from a shoulder injury suffered in his first training session following his close-season move from Real Sociedad was a welcome boost for Arteta with Martin Odegaard currently sidelined.

Gianluigi Donnarumma was back in goal for PSG after missing the last three games with a thigh injury and the Italian had an early test of his fitness as he sprinted off his line to save at Gabriel Martinelli's feet.

Saka, captaining Arsenal for the night, quickly switched the momentum in the hosts' favour when he cut in from the right flank to curl just over from the edge of the area.

Havertz rewarded Arsenal's relentless pressure with the opener in the 20th minute.

Leandro Trossard curled a pin-point cross into the six-yard box and Havertz made a perfectly-timed run behind the visitors' flat-footed defence to bravely head past the advancing Donnarumma.

The Germany forward, who scored Chelsea's Champions League final winner in 2021, endured a difficult start with Arsenal after moving across London for £65 million ($86 million) last year.

But since the start of February, only three Premier League players have more combined goals and assists in all competitions than Havertz's tally of 21 as he banishes the 'waste of money' jibes.

 Composed Arsenal 

PSG's cause wasn't helped by the absence of France winger Ousmane Dembele, who was left out after the 2018 World Cup winner's reported clash with boss Luis Enrique when he was substituted in their win over Rennes on Friday.

Dembele is PSG's most potent attacking force following Kylian Mbappe's move to Real Madrid.

Nuno Mendes tried to provide an attacking spark for the spluttering visitors as the defender's blast from 18 yards smashed off the post and bounced to safety.

But Arsenal were always in control and Saka doubled their advantage in the 35th minute.

Under the guidance of their set-piece guru Nicolas Jover, Arsenal have become lethal from free-kicks and corners, while PSG are notoriously deficient in that area.

So it was little surprise that Arteta's team were able to capitalise on their dead-ball expertise yet again.

Whipping an in swinging free-kick towards Donnarumma's goal, the England forward expected a team-mate to get a touch on his delivery.

Instead, there was enough swerve on the ball that it eluded a gaggle of players and caught the slow-to-react Donnarumma unsighted as it flashed into the net.

Only Bayern Munich's Harry Kane and Real Madrid's Vinicius Junior have been involved in more Champions League goals than Saka since the start of last season.

Trossard shot just wide before half-time as PSG's creaky defence looked more League One than Ligue 1.

Donnarumma made a fine save to keep out Martinelli's volley soon after the interval, but PSG were inches away from grabbing a lifeline when Joao Neves' effort smacked off the bar.

On a rainy evening in north London, Arsenal battened down the hatches in the closing stages as they eased to a significant victory.