Barcelona have a chance of fighting back from a three-goal deficit in Wednesday's Champions League last-16 second leg with Paris St Germain as long as the club's all-time top scorer Lionel Messi is on form, coach Ronald Koeman said on Tuesday.
Barca were beaten 4-1 at home and no side has ever overturned a three-goal deficit in an away leg of the Champions League.
"If Leo is capable of playing one of his best games, everything is possible. He can decide a game at any moment," Koeman told a virtual news conference on Tuesday before his side set off for the French capital.
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But he can't be the only one at the top of his game, everyone needs to be. We also have to have some luck and make sure we take our chances and are as effective in front of goal as possible.
Barca will feel emboldened by their ability to overturn a 2-0 deficit against Sevilla in a Copa del Rey semi-final last week by winning 3-0 after extra-time in the second leg last week.
"I don't think PSG will be scared of us. I'm sure their coach will prepare them as best as he can and ensure they won't think it as an easy game. But the circumstances are totally different this time and it's always easier to play the second leg at home," he said.
"It's always harder to come back from 4-1 away than 2-0 at home but nothing is impossible. We believe in ourselves and we know that Barca have to try to win every game and we're going to show the mentality we have shown for a long time."

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Barca are missing two key centre backs in Gerard Pique and Ronald Araujo.
PSG's Neymar has failed to recover in time from a thigh injury and will be unable to face his former club while Moise Kean, who scored the French side's third goal in the 4-1 win, is unavailable after testing positive for Covid-19.
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