Barcelona boss Xavi has highlighted the difficulties of competing for trophies after Lionel Messi's departure, but says the Catalan giants cannot afford to replicate the recent struggles of Manchester United.

The Blaugrana head into Sunday's match against Rayo Vallecano 15 points behind LaLiga leaders Real Madrid with just 18 points to play for, albeit the buffer to Real Betis in fourth is six.

After previous boss Ronald Koeman left the Catalan giants in ninth position, Xavi has overseen a revival of the team's fortunes and is looking to secure a top-four finish at the end of a transitional season for the club.

Although Xavi acknowledged Barcelona will need to be patient in their pursuit of trophies after losing legendary forward Messi to Paris Saint-Germain, he said the club cannot afford to miss out on Champions League football, highlighting the Red Devils as an example of a household name to have struggled to qualify for the competition.

"It's our reality. This is the post-[Lionel] Messi era, that's difficult in itself," Xavi told a news conference ahead of Sunday's clash with Rayo Vallecano. "He used to win games on his own. We have to be patient. I'm excited to win trophies, but we have to strengthen. We have to be realistic.

"We're in the first year of the post-Messi era, we have to be patient. We've seen a lot of great teams, like at Manchester United, [where] it's been hard for them to come back, to qualify for the Champions League. 

"Barca can't allow that. We have to fight for trophies, we want to compete."

Xavi's arrival has had a positive impact on the Camp Nou outfit, who had briefly threatened to challenge runaway leaders Madrid. 

Among the players to look rejuvenated under Xavi is Ousmane Dembele, whose nine league assists in 2022 place him level with former team-mate Messi as the most creative players in the top five European Leagues this calendar year.

Meanwhile, another of Xavi's trusted first-teamers, Frenkie de Jong, has been linked with a move to Old Trafford after his former Ajax coach Erik ten Hag was confirmed to be taking over from Ralf Rangnick at the end of this season.

Xavi, however, is desperate to keep hold of the midfielder "for many years", saying he has the talent to "mark an era" at Camp Nou.

"Frenkie is very important for me, for the club and for the team," Xavi added. "He is a footballer who has to mark an era, for his quality and personality.

"He is at a very good level since I arrived, and he has to continue scoring goals, [making] assists ... and being a protagonist in the games. He could be one of the best midfielders in the world in the coming years. 

"We have not commented on it [De Jong's future], but if it is up to me, he would continue for many years."