Untouchable Bayern are even better under Pep... Mertesacker sounds ominous warning as European champions enjoy final session before boarding flight for London

Bayern Munich have enjoyed their final training session before boarding the plane for England - and Arsenal's Per Mertesacker has sounded an ominous warning about the 'untouchable' European champions.
The Gunners face Bayern at the Emirates Stadium in the first leg of their last-16 Champions League tie on Wednesday night.
It was at this stage last season that Arsenal won 2-0 in Munich - exiting on away goals following a 3-1 defeat in London - but Bayern have suffered just two competitive defeats since then.
Scroll down to watch Guardiola and his team arrive for check-in at the airport

Thinking game: Pep Guardiola is in pensive mood ahead of the last-16 clash with Arsenal

Game for a laugh: Bayern's players are in relaxed mood as they enjoy a final training session before their flight to London

Guardiola and the Bayern team check-in ahead of Arsenal tie

Wenger says Bayern are favourites but Arsenal have belief to win

Head boy: David Alaba (left) pets Dutch team-mate Arjen Robben

Glove affair: Bastian Schweinsteiger is fit again and ready to face Arsenal

On the slide: Philipp Lahm gets to the ball ahead of Thomas Muller with Pierre Hojbjerg watching on

Warning: Per Mertesacker says Bayern are even better under Guardiola