Xavi said Barcelona had been handed the toughest possible draw after they were paired with Manchester United in the Europa League's knockout round play-offs.
Barca will compete in the Europa League after the turn of the year as a result of their failure to advance from a Champions League group containing Bayern Munich and Inter.
The Blaugrana have now suffered successive group-stage eliminations from the Champions League for just the second time, having also done so under Louis van Gaal in the 1997-98 and 1998-99 campaigns.
Barca were beaten by eventual winners Eintracht Frankfurt in the last eight of the Europa League last term, and Xavi said they had been unfortunate once again following Monday's draw.
"We will have to compete, going to Manchester against a really tough rival," Xavi said ahead of Tuesday's trip to Osasuna in LaLiga.
"It's a historic rival that has grown a lot with the arrival of Erik ten Hag, with great individual players. We have been given the most difficult rival, yet again, in the Europa League.
"There is always a rival who also has the obligation to win, like ourselves. To compete, we have to analyse Manchester. We will try, this club has never won the Europa League.
"It's a massive challenge for us, our players will probably be more motivated against a strong team."
Barca's next European tie will see them reunited with their old foe Cristiano Ronaldo, who has scored 20 goals in 34 games against the Blaugrana, netting against them in LaLiga (nine), the Champions League (two), the Copa del Rey (five) and the Supercopa de Espana (four).
Xavi refuted suggestions the United striker is in decline despite his struggles this season, adding: "He seems to me to be a great player who has marked an era, and he can still make a difference.
"I like to win, I hate to lose, whoever is in front of me. I want to win and be competitive."
Barca have won their last four games against United, including Champions League finals in 2009 and 2011, having won just one of the sides' previous eight meetings in European competitions (D4 L3).