Tito Vilanova is to step down as coach of Barcelona to continue his treatment for cancer, club president Sandro Rosell has confirmed.
Vilanova, who replaced Pep Guardiola as coach of Barca last summer, had a tumour removed from his throat in late 2011, but suffered a relapse a year later.
He underwent another operation on his parotid gland in December before beginning a course of chemotherapy and radiotherapy in New York.
Barcelona said in a statement on their website: "Tito Vilanova will not continue on the Barca bench.
"President Sandro Rosell announced this Friday that the Catalan coach will not start the season."
In a brief press conference that was held with members of Barcelona's first team in attendance, Rosell said: "The news I have is something that you never want to give.
"After evaluating Tito's routine tests, the treatment to follow will be incompatible with being the first-team coach.
"I want to ask for respect for the privacy of this process."
"It's a tough blow but Barca have suffered many blows and we've got through them," added Rosell, who said the club expect to make an announcement on Vilanova's replacement in the coming days.
Reports in Spain earlier today suggested Joan Francesc Ferrer, known as Rubi, could take over in a caretaker capacity.
The 43-year-old joined Barca's coaching staff last month as an assistant to Vilanova and Jordi Roura - who took charge of the first team when Vilanova was absent last season.
Rubi was head coach of Girona last term and led the club to the Segunda Division play-offs, where they lost to Almeria to miss out on a place in the top flight for the first time in their history.
However, there was no mention of Vilanova's possible successor tonight, with Rosell saying: "In next few days the vice-president Josep Maria Bartomeu and sporting director Andoni Zubizarreta will present the new coach, probably at the start of next week."
Barca, meanwhile, cancelled their training session scheduled for this evening and Rosell confirmed they would not now be travelling to Poland for tomorrow's pre-season friendly with Lechia Gdansk.
"We've spoken with all the players in the dressing room and we've decided not to go to Poland tomorrow," he said.
Vilanova, 44, was Guardiola's assistant before being promoted to the top job when the record-breaking coach decided to take a one-year sabbatical from the game last year after winning 14 trophies in four seasons.
In his one campaign in charge of the club, Vilanova led Barca to their fourth Primera Division title in five years, becoming only the second team after Real Madrid to reach the 100-point barrier.
They also reached the semi-finals of the Champions League and Copa del Rey, but lost to Bayern Munich and Madrid respectively.
The manner of the defeat to Bayern was particularly painful for the Catalan giants as they were thrashed 4-0 in Germany before losing the second leg 3-0 in Spain.
Vilanova missed a number of Barca's matches during the second half of the season as he underwent treatment in America, with Roura taking the team in his stead.