Barcelona's Lionel Messi out for around three weeks after rupturing adductor

The Argentinian maestro appeared to suffer the injury after tussling for possession with Atletico defender Diego Godin and was replaced by Arda Turan with 58 minutes gone.

Worse was to follow for Barca as Angel Correa then equalised for the visitors, jinking past Javier Mascherano and steering a shot past Marc-Andre ter Stegen and in off a post.

The news about Messi was a further blow to Barcelona, who were unable to make any inroads into Real Madrid's three-point lead at the top despite Ivan Rakitic heading them in front against Diego Simeone's side in the 41st minute.

The club confirmed the time-frame of Messi's injury in a tweet from the club's official account, and coach Luis Enrique told the Spanish media: "Losing Messi is a loss to us and a loss to football. With Leo we are stronger, but we are still strong without him."

The injury means Messi is set to miss LaLiga matches against Sporting Gijon and Celta Vigo plus a Champions League tie away to Borussia Monchengladbach in between.

Enrique admitted it would be "difficult to protect" Messi with the games coming thick and fast for Barcelona and with Argentina no doubt desperate to have him involved in next month's World Cup qualifiers.

Enrique said Atletico had been a tough nut for his side to crack.

"When there are 11 guys in the area, co-ordinated like that, it takes a lot out of us to break them down," he said in quotes reported by Marca.

"This result is not what we wanted, but we must move on."

There was also an injury for midfielder Sergio Busquets just before Messi suffered his problem, which will somewhat overshadow the ceremony to mark Busquets renewing his Barcelona contract until 2021 on Thursday.

Simeone was very satisfied with Atletico's work as they absorbed plenty of pressure but created plenty of openings themselves.

He told Diario Sport: "We all know it is difficult to get a result at the Nou Camp. In the first half they had a lot of possession and that made it complicated for us to get on the counter-attack.

"The work we did in all the defensive lines was extraordinary. We talked at half-time and the team was able to react in the second half and played with more aggression."