Jürgen Klopp described Lionel Messi as unstoppable after the brilliant Barcelona captain orchestrated Liverpool’s heaviest defeat of the season in the Champions League semi-final first leg. Messi scored twice to bring up a staggering 600 goals for the Spanish champions, 14 years to the day since his debut goal for the club. His second of the game – an incredible free-kick swept into the top corner of Alisson’s goal from distance – gave Barcelona a 3-0 advantage that Klopp accepted would be difficult to overturn in Tuesday’s second leg at Anfield. Liverpool can consider the scoreline harsh. Sadio Mané and Mohamed Salah missed excellent chances to change the complexion of the tie but their manager, while proud of the performance, admitted there was no answer to Messi. “In these moments he is unstoppable,” said Klopp. “We couldn’t defend the free kick. What a strike. “The second goal was probably not the nicest in the career of Lionel Messi but it shows his skills that he is even there in that moment. Apart from that I was happy in how we defended the whole Barcelona team. I am a big admirer of them, as is everybody, but my boys didn’t show…