Serie A champions Napoli will be without last year's player of the season Scott McTominay for Wednesday's Champions League opener against Arsenal as the former Manchester United midfielder has undergone heart surgery.
Arsenal begin their Champions League campaign with a trip to Napoli on Wednesday, with Riccardo Calafiori confident their start can provide momentum at the Stadio Diego Armando Maradona.
Aston Villa scored three goals in the first half and then held on to beat Club Brugge 3-2 in their UEFA Champions League opener in Belgium on Tuesday.
Arsenal have been handed a demanding UEFA Champions League league-phase campaign, with Real Madrid and Bayern Munich among the biggest names standing in their way.
Vincent Kompany has made Bayern Munich's ambitions clear ahead of the new season, saying the club's main objective is to win the UEFA Champions League after strengthening the squad during the current transfer window.
Jonathan Tah has said Bayern Munich are determined to carry the momentum from last season into the new campaign as the Bundesliga champions set their sights on more domestic success and a stronger challenge in the Champions League.