Ahead of Glasgow Celtic&rsquo;s showdown with Barcelona in the Champions League, Nigeria international Efe Ambrose reckons that the Spanish side will be a tough nut to crack even if they are without Lionel Messi.<br /><br />The Argentina superstar picked up a thigh injury this past weekend against Almeria, and thus will not be available for selection.<br /><br />&ldquo;It&rsquo;s not just facing Messi, it&rsquo;s facing Barcelona.<br /><br />&ldquo;You can&rsquo;t pick one player from their squad and say he is not dangerous. They all are.<br /><br />&ldquo;We have to look at stopping Barcelona, not Messi or Xavi or anyone else.<br /><br />&ldquo;They are different team from last season, with a different coach, different tactics and a different system,&rdquo; said Efe Ambrose.<br /><br />Efe Ambrose, 24, has only missed one game in the Champions League this term, which was the away loss to Shakhter Karagandy in August.<br />