Slovan Bratislava 0-4 Manchester City
Manchester City put up a dominant showing at Slovan Bratisvlava and cruised to a comfortable 4-0 win.
Stefan Ortega, John Stones, Matheus Nunes, Phil Foden, Savinho and Jeremy Doku came in as City named six changes from the weekend draw at Newcastle United.
Ilkay Gundogan opened his account for the club since returning through a first-time volley which ricochet off Kyriakos Savvidis and wrong-footed Dominik Takac to find the net.
Foden made it two with just over 15 minutes played when he burst well ahead after a pass from Doku and curled well out of the reach of Takac.
The Citizens enjoyed complete control and added a third after Erling Haaland raced onto a through ball from Lewis to finish calmly past Takac.
Youngster James McAtee, who got a run-out from the substitutes bench, made it four after getting on the end of Foden's inch-perfect delivery to slam home with ease.
Arsenal 2-0 Paris Saint-Germain
Arsenal collected their first win in the league phase of the UEFA Champions League with a 2-0 victory over Paris Saint-Germain on Tuesday evening.
The Gunners were unchanged from the win over Leicester City, although new signing Mikel Merino was on the bench, as the absence of Ousmane Dembele set out the PSG starting contingent.
Kai Havertz broke in at the far post after the opening 20 minutes and managed to get onto Leandro Trossard's floated ball to head beyond Gianluigi Donnarumma.
Another followed the Premier League giants ten minutes to halftime when a well-struck free-kick from Bukayo Saka beat the wall and sneaked past Donnarumma.
FC Barcelona 5-0 Young Boys
FC Barcelona made light work of Swiss outfit Young Boys to register their first win in the tournament through a dominant 5-0 victory.
With Eric Garcia out suspended, the Blaugrana welcomed back Inigo Martinez, Alejandro Balde, Marc Casado, Raphinha and Lamine Yamal and aimed to recover from the disappointing loss to Osasuna.
Polosh sharp-shooter Robert Lewandowski marked the proceedings through a first-time finish from close-range after meeting a Raphinha lay-off.
The latter then added a second goal when he finished off a rebound from a loose ball in the area with Inigo Martinez making it three after heading in corner-kick from Pedri.
Lewandowski made it a complete one-sided affair shortly after the break when he headed in from close-range following a flick from Martinez.
Young Boys continued to fell on their sword as the host made it five after a clearance by Mohamed Ali Camara unfortunately found his own net, seeing Barca cruise to victory.
Inter Milan 4-0 Red Star Belgrade
Inter Milan picked up their first win the league phase format after trouncing Red Star Belgrade 4-0 at the San Siro Stadium.
Captain Lautaro Martinez and Marcus Thuram started on the bench, with Nicolo Barella unavailable through injury as veteran Marko Arnautovic got the starting nod and partnered Mehdi Taremi.
Turkish skipper Hakan Calhanoglu lid up the venue on eleven minutes when he drilled a powerful free-kick into the top corner to give the host the lead.
With the lead at break, the Nerazzurri bagged a second thereafter as Taremi capitalised on a stray pass and rolled across to Arnautovic to finish easily.
Inter were in complete control from then and unsurprisingly compounded the visitors' woes when Martinez came off the bench to tuck in a layoff from Taremi.
Taremi wasn't prevented any part of the action and made it four through a pin-point effort from the penalty spot late on and saw the Italian champions to an emphatic victory.
Bayer Leverkusen 1-0 AC Milan
Seven-time champions AC Milan came unstuck on the road to German champions Bayer Leverkusen and succumbed to a 1-0 loss.
One change from Milan saw Ruben Loftus-Cheek come in for Alvaro Morata, while Leverkusen dropped Andrich and Terrier to give Amine Adli and Aleix Garcia a run out from the onset.
Leverkusen seemed to have gone ahead in the opening stages through a smart finish from Victor Boniface following Jeremie Frimpong's ball, but it was disallowed for offside.
As the first period finished score-less, the host did go ahead when the self-same Boniface pounced on a spill by Mike Maignan following Frimpong's shot and tapped in an unguarded net.