Pep Guardiola's former team meets his current employers in Wednesday's friendly when European champions Bayern Munich host Spanish giants Barcelona, who are on the hunt for a new manager.
Barcelona arrived in Munich without a head coach after Tito Vilanova resigned on Friday, as he battles against cancer, but the Spanish giants are expected to announce his successor soon.
Vilanova's assistant Jordi Roura will be in charge at Munich's Allianz Arena and the 45-year-old took charge of Barcelona from December to April when Vilanova was receiving treatment.
After Guardiola won 14 titles between 2008 and 2012 at Barcelona, the pre-season run out has added spice, especially given recent events which have strained relations between the two European powerhouses.
Guardiola took charge of Bayern last month, amid great fanfare, after the Bavarians lured the 42-year-old to Munich following his year's sabbatical in New York.
Guardiola has already poached Spain Under-21 captain Thiago Alcantara from Barcelona to bolster his star-studded midfield which includes Netherlands' Arjen Robben and France winger Franck Ribery.
But Guardiola stirred up bad blood with his former bosses earlier this month when he accused the Barcelona board of trying to "damage" him.
Guardiola lashed out in a press conference, making allegations against the board, which were later refuted, that he had snubbed Vilanova while he was being treated for cancer in New York.
"I will never forget that they used Tito's illness to cause me damage, because it's a lie that I never saw him in New York," he said.
With relations strained off the field, there is plenty of spice on it, although both teams are likely to name weakened teams.
Absentees from both sides
Bayern's Germany stars Bastian Schweinsteiger and Mario Gotze are both recovering from injury, while neither team is expected to have their FIFA Confederations Cup stars in action.
Both Barcelona's new Brazil star Neymar and Spain's Carles Puyol, who is working his way back to fitness after knee surgery in March, are expected to sit it out.
Senior stars Javier Mascherano, Adriano Correia, Alex Song and Alexis Sanchez are likely to feature among a host of reserves, while Argentinian superstar Lionel Messi is set to play some part.
Barcelona have something to prove against Bayern having been humbled 7-0 on aggregate in last season's UEFA Champions League finals when the Germans backed up a 4-0 win in Munich with a 3-0 rout at the Camp Nou.
Having already chalked up wins over Bundesliga opposition Hamburg and Borussia Monchengladbach in a pre-season tournament over the weekend, the Barcelona friendly is a big test for Guardiola's new-look Bayern.
He has introduced a 4-1-4-1 system, from the 4-2-3-1 formation which won last season's treble, and switched Germany captain Philipp Lahm from right-back into midfield with France winger Franck Ribery up front.
The game's kick-off time has been brought forward to 1830 local time to allow home-team fans to watch Germany's women in the semi-final of the 2013 UEFA Women's EURO.