Germany legend Lothar Matthaeus warned Bayern Munich to defend deeper in Sunday’s Champions League final against Paris Saint Germain or risk blowing the treble.

After demolishing Barcelona 8-2 in the quarter-finals, Bayern endured a nervous start to Wednesday’s 3-0 semi-final win over Lyon, who wreaked havoc early on by getting in behind the Germans’ defence.

“Bayern had a harder time against Lyon than against Barcelona,” former Bayern midfielder and West Germany captain Lothar Matthaeus said on Wednesday.

“If they play like that on Sunday, they won’t win the Champions League or live up to the role as favourites.

“Paris have more quality than Barcelona and Lyon, they also have enough players who can put the ball into the key spaces.”

Lyon squandered golden chances when quick passes into space initially forced Bayern onto the back foot.

Memphis Depay fired wide and Toko Ekambi hit the post for Lyon in the opening 15 minutes before Serge Gnabry calmed Munich nerves with two first-half goals.

A late Robert Lewandowski header sealed the win to extend Bayern’s winning streak to 21 matches.

Bayern’s ability to score is without question after racking up 42 goals in 10 European matches, 15 of which by Lewandowski, the Champions League’s top-scorer, while Gnabry is on nine.

Data Check: The stunning numbers behind Bayern Munich’s incredible Champions League campaign

Space to exploit

Yet their defence struggled on occasion, raising concerns what PSG’s forwards Neymar, Kylian Mbappe and Angel Di Maria could do with space to exploit.

“In attack, they still have their quality, but at the back they need to be more stable,” said Matthaeus.

“Maybe against Paris they shouldn’t defend so high, because Paris will use the speed of Neymar and Mbappe”.

Bayern’s head coach agreed with Matthaeus.

“We were lucky to hold out in the first phase of the match,” admitted Hansi Flick, who seemed more relieved than euphoric to reach the final.

“We’ll have to see that we organise the defence a little differently.

“Our great strength is pressuring on the opponent and I think that we will succeed against Paris as well.”

Centre-back David Alaba saids Bayern’s pressing game - forcing opponents into mistakes in their own half - carries a certain risk, but they can adapt against PSG.

“Of course, we play a game which always carries a high risk because we stand so high (up the pitch),” said the Austria defender.

“You can’t defend every ball, we will look at the (Lyon) game and make our analysis.”

‘Clay feet’

Specialist German magazine Kicker described Bayern as “a giant with feet of clay” on Thursday, pointing to Thiago Alcantara’s poor pass that led to Depay’s chance and Alphonso Davies’ lapse in concentration before Ekambi hit the post.

Joshua Kimmich was guilty of poor positioning on occasions, but Benjamin Pavard could replace him at right-back against PSG after recovering from injury.

Bayern’s back four will be under pressure to cope with the Parisians’ pace, especially centre-backs Alaba and Jerome Boateng, who came off against Lyon with a leg knock.

Former Bayern and France defender Bixente Lizarazu spelt out how to counter PSG’s attack.

“When Mbappe is there, the opposing defence moves back twenty metres. That changes everything,” said Lizarazu, 50, who won six Bundesliga titles in Munich.

“You have to know how to defend deep and not everyone knows how to do that.”