Barcelona will have to continue their march at the top of La Liga with coach Tito Vilanova at the sidelines after the club revealed Wednesday he has suffered a relapse of a tumour on which he was operated just over a year ago.

The 44-year-old who took over from Pep Guardiola at the beginning of the season was thought to have fully recovered from surgery last November to remove the growth on his parotid gland, and he was back at work within 15 days.

However, after an operation on Thursday it is thought he will have treatment for at least six weeks and may not be available to return to work during that time.

Until then, Sporting director Andoni Zubizarreta confirmed on Thursday, the side will be led by Vilanova's team, with his assistant Jordi Roura at the helm.

"Without going into too much detail about the sporting side today and whether we win or not at Valladolid on Saturday, just to say we'll continue with our coaching staff and our way of working, we'll be in extraordinary hands and Tito I'm sure will be watching us on TV," he said.

Barca president Sandro Rossell added "the most important thing for the club at this moment is the full recovery of Tito".

Vilanova has led Barcelona to the most successful start to a season in La Liga's history, with 15 wins and one draw in 16 matches so far.

With the final round of La Liga games of 2012 brought forward to allow the players an extra day of Christmas holidays, Barca will make it a great finish to the year, on the pitch at least, if they take three points at Valladolid on Saturday.

Last weekend's win over closest rivals Atletico Madrid increased the Catalan side's lead to nine points at the top of La Liga and with Real Madrid's surprise draw with Espanyol leaving 'los blancos' 13 points back in third, for some the title is already destined for the Nou Camp in May.

That win was followed with the news on Monday that Carles Puyol and Xavi Hernandez will stay at Barca until at least 2016 and Lionel Messi until 2018, and it was all looking positive until Wednesday's shock news.

Last Sunday's clear dominance over their closest rivals Atletico Madrid, especially in the second-half, in the 4-1 win, left most observers concluding that it is the Catalans' title to lose.

The win also secured Barca's status as La Liga's 'Winter Champions', a title given to the side top of the league with half the calendar completed. With only 16 games played Barca still have three games to play until the halfway stage.

Atletico's challenge seems to have ground to a halt with defeats at neighbours Real and now Barcelona since December began.

They play Celta Vigo on Friday in the hope of continuing an excellent run of eight home wins since the league began, to keep up some sort of pressure on the Catalans.

Meanwhile Real Madrid face a tricky trip to fourth placed Malaga less than a week after manager Jose Mourinho said the title was "almost impossible now."

Defeats at Getafe, Sevilla, and Betis followed by the draw last Sunday have left Madrid so far adrift and Malaga

One player the 'Merengues' missed last Sunday was French forward Karim Benzema.

Benzema is closer to a return than colleague Gonzalo Higuain, but could still miss the trip to Malaga with a foot injury. However he has plegded his future to the club this week, despite his name being linked with Paris Saint-Germain.

"I don't know anything about any speculation,if the president offers me an contract extension I'd sign straightaway, I'm very happy at Real Madrid, it's where I want to be," he said.

"It's the biggest club in the world and our adventure has not ended, I won't leave Madrid until we win the club's tenth Champions League, everybody here wants that one and I want to be part of it", he added.

Malaga come into the game with the best defensive record in the league having conceded only 10 in 16 games and full-back Nacho Monreal is confident.

"We're going to be up for the Madrid match, we're doing well, we're at home and we know that Madrid is not going too good, but they're a good team and it will be difficult. I just hope we can take our chances and get the three points," he said.