Lionel Messi's new club Paris St Germain will play Manchester City, managed by the Argentine's former Barcelona coach Pep Guardiola, after being drawn together in Champion's League Group A on Thursday.
Messi joined Qatari-owned PSG, who will also face Bundesliga side RB Leipzig and Belgium's Brugge, from Barcelona this month after the Spanish side were unable to afford a new contract for the forward.
The draw pits two of European soccer's wealthiest teams against each other once again as they both seek a first Champions League title, with City beating the French side 4-1 on aggregate in last season's semis.
Abu Dhabi-owned City went on to lose the final to Premier League rivals Chelsea, who were drawn in Group H against Juventus, Zenit St Petersburg and Malmo.
City have yet to lose to PSG in the Champions League but Messi has also scored more goals against them -- six in six games -- than any other side in the competition.
"After the Porto, Liverpool, Atletico Madrid group, our group is probably the second most difficult one," said City's director of football Txiki Begiristain.
"Some of the big names in football are going to be out. That is the magnitude of this competition."
Spanish champions Atletico Madrid and Liverpool were drawn in a tricky Group B with former winners Porto and AC Milan, while Real Madrid play Inter Milan, Shakhtar Donetsk and Moldovan debutants Sheriff Tiraspol in Group D.
Six-times winners Liverpool and manager Juergen Klopp will at least have fond memories of Atletico's Metropolitano stadium after winning the 2019 title there against Tottenham Hotspur.
"I laughed, to be honest, pretty loud because it is a tough group obviously," Klopp told Liverpoolfc.com.
"We played, I don't know how often, already against Porto, so they will be waiting for us. We have obviously a little bit of (an) open bill with Atletico, and AC Milan, a historical one obviously.
"I think our supporters should be looking forward to it -- we do, for sure."
AC Milan coach Stefano Pioli, whose club beat Liverpool in the 2007 final after losing memorably in 2005, said it was certainly a "stimulating" group.
"Together in our group we have 15 Champions League wins. We expected it, this is the Champions League and we can't wait to start. We will try to do important things," he added.
Inter, Shakhtar and Real were also in the same group last time around with the Italian side finishing last.
Barcelona were drawn in Group E with Bayern Munich, Benfica and Dynamo Kyiv.
Manchester United will have another meeting with Spain's Villarreal, a repeat of this year's Europa League final, in Group F along with Atalanta and Swiss side Young Boys.
Sporting Lisbon drew Borussia Dortmund, Ajax and Besiktas in Group C with Lille, Sevilla, Salzburg and VfL Wolfsburg together in Group G.
The first group games will be on Sept. 14 and 15 with the final played in St Petersburg on May 28 next year.