Andreas Christensen admits Chelsea must fix their leaky defence immediately to ensure their season does not fall apart.

The European champions were outplayed last night as a Karim Benzema hat-trick put Real Madrid in firm control of their Champions League quarter-final. 

Christensen was an unused sub last Saturday as Brentford won 4-1 at Stamford Bridge but was restored to the starting line-up against Real before Thomas Tuchel hooked him at half-time as he shuffled his pack. 

The Dane said: "We weren’t at our top level. 

"We started good for 10 or 15 minutes, good energy with the crowd behind us — and they stayed behind us the whole game — but Real successfully took the tempo out of the game. 

"We have conceded seven goals now in two games, which is not normal for us. 

"It’s not just about this game, we did it as well at the weekend. We have to fix it and we have to do it quick."

Until facing Brentford, Tuchel's side had successfully managed to keep on track despite the noise created by the ongoing bidding process to find new owners for the club. 

The world champions were expected to bounce back from their Premier League humbling at the hands of the Bees but were dealt another lesson by red-hot Benzema. 

Christensen, 25, added: "It’s two goals, it’s still going to be very difficult but it can’t be worse than this. 

"We have to go there and make a big performance. We have to try and turn it around but it’s going to be difficult. 

"We weren’t on top and we know that. But we have nothing to lose so we have to go there, put in a big performance and hopefully turn it around."

The Blues face Southampton at St Mary's on Saturday before heading to the Bernabeu for the return leg next Tuesday. 

They then head to Wembley to tackle London rivals Crystal Palace in the FA Cup semi-finals on Easter Sunday, having lost the Carabao Cup final there to Liverpool in February. 

And a concerned Tuchel is desperate to see his side get back on track, particularly while there is a chance to add more silverware to the European Super Cup and Club World Cup they won earlier this season. 

He said: "I don’t really have an explanation because before we had a long winning streak and were very competitive.

"It’s alarming because it’s two games and seven goals, but nothing has changed."