Real Madrid will be the team to beat again in the European Champions League as they chase their 16th title, but a new, expanded format means pretty much everything else has changed, including the introduction of four extra clubs.
As if Real - winners of six of the past 11 finals - weren't formidable enough, coach Carlo Ancelotti will now be able to call on France's star striker Kylian Mbappe against Stuttgart on Tuesday after his move from Paris Saint-Germain.
Also available to play at the Santiago Bernabeu after injury are England's Jude Bellingham, fellow midfielder Aurelien Tchouameni, of France, and Brazilain central defender Eder Militao.
Real beat another German side, Dortmund, 2-0 at Wembley in June's final but clubs and supporters are getting to grips with the first change in the competition's format since 2003-04, when the round of 16 stage was introduced.
The familiar group stage - featuring eight pools of four, with teams playing each other home and away - has been replaced with a league comprising 36 teams.
Sides will compete in one single league phase which won't finish until the end of January, with each team playing eight games against eight different opponents.
The top eight teams will qualify automatically for the last 16, while the teams that finish between ninth and 24th will compete in a new knockout playoff to complete the round of 16.
Teams finishing 25th and below will be eliminated and there is no longer relegation to the Europa League.
In announcing the changes, governing body UEFA claimed every fixture would make an impact on the league table, avoiding dead rubbers on the final matchday of four-team groups, though whether that proves the case remains to be seen.
There are six games each on Tuesday, Wednesday and Thursday this week. Tuesday's games include Juventus versus PSV and Bayern Munich - who will host the 2025 final at the Allianz Arena - against Dinamo Zagreb.
The new format does nothing to address the hectic schedule of top players, something Ancelotti blamed on Monday for having so many injuries among his squad.
"The calendar is too demanding," he said.
"If the governing bodies don't start thinking that the players get injured because they play too much, we have a problem. I ask that the number of matches be reduced to have more attractive competitions."
