Real Madrid 3-1 Stuttgart
Holders Real Madrid thumped Stuttgart 3-1 in the opener of the new UEFA Champions League format on Tuesday evening.
Kylian Mbappe, who arrived in the off-season, headlined the defending champions line-up and flanked by Rodrygo Goes and Vinicius Junior.
After a goalless first half, Los Blancos took the lead when Mbappe capitalised on a reverse pass across the area from Rodrygo and bundled in the net.
Stuttgart wasn't overawed by the occasion and levelled matters later on when Deniz Undav nodded in from the back-post following a corner-kick.
Los Blancos regained control though in the closing seven minutes when Antonio Rudiger jumped high to meet a Luka Modric corner and nodded in the far post.
Youngster Endrick, who also joined in the close-season, made it three and opened his account in the tournament with a stern finish into the bottom-corner.
AC Milan 1-3 Liverpool
Liverpool also started the new format of the tournament impressively in a 3-1 triumph over AC Milan at the San Siro Stadium.
Mohamed Salah, Luis Diaz, Diogo Jota set out the Reds front trio, but the host had potent man too in new signing Alvaro Morata, Christian Pulisic and Rafael Leao.
Pulisic, who faced the Reds during his time with Chelsea in the past, opened proceedings on three minutes through a swerving shot across the area that rolled past Alisson Becker and in the net.
Liverpool pulled level in the middle of the first half after defender Ibrahima Konate towered unchallenged in the area to head in a Trent Alexander-Arnold free-kick.
Fellow defender Virgil Van Dijk made it two for the Premier League giants when he rose high at the near post to meet a Konstantinos Tsimikas corner and nodded in.
The Italian giants weren't able to bounce back and conceded again in the midway stage of the second stanza courtesy of a rasping finish by Dominik Szoboszlai.
Bayern Munich 9-2 Dinamo Zagreb
Harry Kane scored four times as Bayern Munich crushed a hapless Dinamo Zagreb 9-2 in their tournament opener.
It was a debut for Belgian-born Vincent Kompany as coach of Bayern in the tournament, with England's Harry Kane up top and the recently returned Leroy Sane on the bench.
Kane broke the deadlock earlier on with a spot-kick following a foul in the area - leaving Raphael Guerreiro to make it two through a half-volley before Michael Olise's header ensured a third.
After a one-sided half, the visitors hit back two minutes following the interval through Bruno Petkovic and Japanese international Takuya Ogiwara.
Bayern regained the two-goal cushion though when Kane fed on a loose ball from point-blank range and fired in, with Olise coming inside to make it five soon thereafter.
Kane registered a hat-trick in the final quarter with yet another strike off the penalty spot following a foul and soon bagged a fourth of his own from another spot-kick.
The sixth-time champions were far from done as substitute Sane came on to make it eight and Leon Goretzka stepped up in added time to complete the annihilation and a resounding day at the office.
Juventus 3-1 PSV Eindhoven
Juventus made a winning start to the return of the continent's club tournament after brushing off Dutch side PSV Eindhoven 3-1 in Turin.
Two alterations for the home team from the draw with Empoli in Serie A over the weekend saw Weston McKennie and Michele Di Gregorio in for Mattia Perrin and Douglas Luiz respectively.
Rising star and Turkish-born Kenan Yildiz broke the deadlock earlier on with a ferocious finish from a clever position - giving the opposite number Joel Drommel no chance.
Juve were on a roll just ahead of the half-hour mark and duly doubled the lead after McKennie enjoyed acres of space in the area and redirected a flowing passing in the net.
It got worse for the Eredivisie charges when off-season signing Nicolas Gonzalez ran onto a defence-splitting pass from Dusan Vlahovic and finished comfortably.
PSV got a consolation in the dying minutes as Spanish international Ismael Saibari retrieved possession from a decent position and fired in, but Juve still emerged victorious.