The Premier League is out of reach for Manchester United this season, with Xavi warning Jose Mourinho and Co. to lower their expectations.
United's title hopes took a blow on Sunday, humiliated 4-0 by Chelsea in Mourinho's return to Stamford Bridge.
The embarrassing result left United seventh in the Premier League, six points adrift of table-topping Manchester City, whom they host in the fourth round of the EFL Cup on Wednesday.
And former Barcelona midfielder Xavi has urged United to set their sights on the EFL Cup, as well as retaining the FA Cup.
"The domestic competitions have to be everything for United and Mourinho this season," Xavi said in quotes attributed to the Mirror.
"I don't think this season they can win the Premier League. These competitions are their hope for a trophy.
"Once Mourinho has had another transfer window, maybe they'll be ready, but for now they must secure a finish in a Champions League spot - that's where United belong."
Xavi added: "Sometimes, when things don't go well for Mourinho, he wants war not football - like when he was at [Real] Madrid - and I hope we don't see that again in England."
United renew hostilities with City in a midweek derby, having already suffered a 2-1 loss to their arch-rivals in the Premier League in September.
Pep Guardiola's City head to Old Trafford in the midst of a five-game winless run in all competitions.
Xavi, however, believes his former boss will still lead City to Premier League glory in 2016-17.
"Both coaches are going to want to win this game," said Xavi. "I don't believe this is a competition they will not take seriously.
"Pep will not be worrying, that's not his way - but he will not have been happy with recent results - and a good win against the biggest rivals could put them on a good run again.
"Pep will also want to win his first competition with City, that will be important for him. Even with City dropping some points in the league, I still think under Pep they'll be champions this season."