bundesliga.com previews the Catalan's hotly anticipated homecoming...
In what is set to be a particularly emotional occasion for Guardiola - who won 31 titles as a player and coach in his Barcelona days - Bayern will be looking to register a positive result and ideally notch an away goal ahead of next week's second leg at the Allianz Arena, where they are unbeaten in this season's competition.
French defender Jeremy Mathieu is out with an achilles problem, while former Borussia Mönchengladbach goalkeeper Marc-Andre ter Stegen and ex-FC Schalke 04 midfielder Ivan Rakitic are expected to start, with in-form attacking triumvirate Lionel Messi, Neymar Jr and Luis Suarez leading the line.
Holger Badstuber, David Alaba, Arjen Robben, Franck Ribery and Sebastian Rode have all been ruled out. Polish striker Robert Lewandowski (l.), meanwhile, has been included in the squad, but will have to wear a protective mask after suffering a broken nose and upper jaw in last week's DFB Cup semi-final defeat to Borussia Dortmund.
Suarez (r.) has taken time to adapt to his new surroundings, but the mellowed Uruguayan has hit top form in recent weeks. Operating alongside Messi and Neymar, the former Liverpool FC striker has scored ten times in his last eight appearances, and twice away to Paris St-Germain in the previous round.
Thiago Alcantara will be out to show Barcelona exactly what they're missing after being allowed to join Guardiola in the Bavarian capital in summer 2013. The 24-year-old has been running the show in recent weeks and will provide the vital link between defence and attack on his first outing back at Camp Nou since leaving the club.
Messi: "We're in the semis against a strong side in Bayern. We don't like the way we lost against them previously [in the 2012/13 7-0 aggregate Champions League semi-final loss] but the teams are different and this match will be different to that one too. We don't have excuses now and neither do Bayern."
Thomas Müller, l.: "We believe in ourselves, although we know it won't be easy. But it's the same in every Champions League match. There are no favourites."
Jerome Boateng: "We face an exceptional forward line and we'll have to deal with them as a team."
Barca beat PSG 5-1 over two legs in the quarter-finals, while Bayern overturned a 3-1 first-leg deficit by thrashing FC Porto 6-1 on home soil. La Blaugrana coasted to victory in their three subsequent league games by an aggregate score of 16-0, but Bayern have only won one of theirs, before losing to BVB and Leverkusen last week.
Bayern have faced Barcelona twice before in European semi-finals, winning on both occasions and going on to lift the trophy, in the 1995/96 UEFA Cup (4-3 on aggregate) and the 2012/13 Champions League (7-0 on aggregate). Barca have, in fact, never got the better of Bayern in a competitive fixture without the help of Guardiola.
Barcelona: Ter Stegen - Alves, Pique, Mascherano, Alba; Busquets, Rakitic, Iniesta - Messi, Suarez, Neymar
Bayern: Neuer - Rafinha, Boateng, Benatia, Bernat - Lahm, Alonso, Thiago Alcantara - Müller, Lewandowski, Götze