Royal Antwerp 3-2 Barcelona: Barca slump to third defeat in seven games as pressure mounts on Xavi despite finishing top of their group... with Belgian side scoring in stoppage time to claim first Champions League win

Troubled Barcelona missed out on €2.8million (£2.4m) of UEFA prize money, losing their last Champions League group game 3-2 to Royal Antwerp, with the sort of shambolic display that will make them the side many teams want in Monday's draw.

They top Group H but signed off with a dismal performance that – coming three days after a 4-2 defeat by Girona – leaves huge doubts over Xavi's long term future as coach.

He's not being helped by interference from above – President Joan Laporta and Director of Football Deco are understood to have applied pressure on him to travel to Belguim with Robert Lewandowski who he wanted to rest.

The Pole ended up starting the game and when he was replaced by 17-year-old Marc Guiu with 20 minutes left the teenager scored with a header from a free-kick. His goal made it 2-2 and looked like saving the team from defeat but there was still time for more woeful defending and George Ilenikhena scored in injury time to give Royal Antwerp a well-deserved win.

Barcelona were behind inside two minutes. It could have been worse – they could have been behind inside one minute. Seventeen year-old Hector Fort was making his debut at right back and when he lost possession Barça were lucky the cross flashed harmlessly across the face of the area.

But seconds later Inaki Pena played the ball out to Oriol Romeu who was under pressure inside the penalty box and his touch was as poor as the keeper's pass. Eighteen year-old Arthur Vermeeren pounced on it and lashed it past Pena. It was the third time this season Barcelona have conceded inside two minutes – twice in the league they have let in goals inside 20 seconds.

As well as teenager Fort in defence Xavi had picked 16-year-old with Lamine Yamal. But the bigger news was that Lewandowski started, having not originally been Xavi's squad. President Laporta had pulled rank and advised the coach to take Lewandowski, as well as Ilkay Gundogan and Ronald Araujo who Xavi also wanted to rest.

The coach explained away the decision to include the three players not originally down to travel to Belgium by saying the itinerary of the trip had changed. He was barely noticed in the first half an hour and when Barcelona equalized it was Ferran Torres who scored it.

Yamal made it threading a pass through the lines of Antwerp's retreating defence to find the former Manchester City striker who took one touch and then scored past Jean Butez.

Whatever Xavi said at half time it had the reverse effect because Antwerp scored from their first chance only for a raised flag for offside to cancel it out. Jules Kounde completely missed the cross from the Antwerp right allowing Vincent Janssen to send his shot past Pena.

There was another let-up moments later when Sergio Roberto was shown red for a reckless challenge on Mandela Keita only for the referee Marco Guida to downgrade the card to yellow after checking it pitch side.

Janssen was not to be denied his goal and with Antwerp's next raid on Barça's fragile defence Xavi's team cracked. It was Romeu again and this time he couldn't point to having received a poor pass. He just lost possession on the edge of the area and when Alhassan Yusuf played quickly through to Janssen he made it 2-1.

It was practically Romeu's last contribution as Xavi brought on Gundogan, Cancelo and Pedri for Lopez, Font and Romeu.

With 20 minutes left Lewandowski was taken off and replaced by Guiu. Presumably Laporta had wanted him in the team to secure that prize money for winning the game, for all that he had managed to help Barcelona do that, he might as well have stayed at home.

Guiu scored but so did Ilenikhena and so Barcelona ended their European group campaign with a loss. They have now conceded seven goals in two games and must win at Valencia this weekend to silence the talk of crisis.