The footballing world is likely to come to a standstill on Tuesday as Lionel Messi and Cristiano Ronaldo duel for potentially the final time when Barcelona host Juventus in the Champions League.
The two titans of the modern game, who split ownership of the Ballon d'Or between 2008-2017, were the talismans of Spanish giants Barcelona and Real Madrid until Ronaldo left the Spanish capital for Juventus in 2018.
Since then, the football world has waited eagerly to see the pair pitted against each other again.
Those hopes were frustrated earlier in the group phase, with Ronaldo missing Barcelona's 2-0 win in Turin after testing positive for Covid-19. Messi scored with a penalty. They are poised to meet again.
Both sides have already qualified for the last 16 from Group G but Juventus can overtake Barcelona if they win at Camp Nou by three goals or more, or by any two-goal margin greater than 2-0.
Ronaldo and Messi are in the latter phases of their careers, at 35 and 33 respectively, but both retain their elite status.
The Portuguese is thriving in Italy, having quickly become key for Juventus, who presented him with a commemorative shirt on Saturday to recognise his 750th career goal, ahead of a 2-1 win over neighbours Torino.
With eight goals in six appearances this season for Andrea Pirlo, Ronaldo is showing no signs of slowing down. By contrast, Messi is struggling in Spain.
The Barcelona forward tried to escape this summer but his club refused to let him leave and Messi appears an uncomfortable fit in new coach Ronald Koeman's tactical plans, and far from his decisive best.
Barcelona are enduring their worst start to a league season for 33 years and Messi's inconsistency is part of the problem, with four goals in 10 appearances and two of those from the penalty spot.
That's not the only worry for Barca. Injury-prone French forward Ousmane Dembele tweaked his right hamstring in the loss to Cadiz. Spanish media estimated he would be out for one to two weeks.
Messi inspires Barca to win over Ronaldo-less Juve
Dembele suffered a string of serious injuries to his right hamstring last season and appeared in only nine games for Barcelona. This season he has already played 12 times and scored four goals, including one in a Champions League victory at Ferencvaros on Wednesday.
He joins a growing injury list at the Camp Nou.
Teenage phenomenon Ansu Fati, Sergi Roberto and defender Gerard Pique all suffered serious injuries in November and will be out until next year. Defender Samuel Umtiti is another long-term casualty.
Manager Ronald Koeman has been rotating other players who are carrying knocks, including goalkeeper Marc-Andre ter Stegen and defender Clement Lenglet.