The diminutive Argentina captain excelled against Real Madrid in the semi-final and has looked comfortable in this unorthodox position ever since.
Javier Mascherano happy to plug the gap for Barca
BARCELONA // Following their penultimate training session before leaving for London, the Barcelona coach Pep Guardiola stood on the Camp Nou pitch consulting fellow coaches. He appeared deep in thought.
Maybe it was the volcanic ash cloud which was troubling him. Worried about the impact of a road journey, Guardiola decided to bring Barca's departure for London forward by two days.
Or maybe it was over possibly his sole remaining dilemma: who to start alongside Gerard Pique in the centre of Barca's defence against Manchester United.
Eric Abidal and Javier Mascherano are the two players in contention. One was enjoying the best form of his Barca career until a cancerous tumour was found in his liver in March. Six weeks after an immediate operation, Abidal has returned to play for the first team. But has he had enough games to be risked in the biggest game in club football?
The other option is Mascherano. The diminutive Argentina captain, 26, was used as an emergency stand-in against Real Madrid away in the semi-final. He excelled and has looked comfortable in this unorthodox position ever since.
Mistakes have been rare from the composed midfielder signed from Liverpool for £22 million (Dh132m) in August, but he still does not know if he will be starting.
"We are lucky that the key players for us, like Abidal and [Carles] Puyol, are back, so I don't know if I am going to play or not. I am just ready to help the team," he said.
"It is not my position, obviously, but when you don't play in your position you try and adapt, and show other qualities. I know that I am not going to win balls in the air. I am small, but when I have played in defence I have given everything for the team."
A surprise signing, Mascherano had only moderate impact at Barca until his recent defensive cameo.
"I'm really happy with my first season here," he said. "I have won the league and we reached the final of the Copa del Rey. Now we're in the Champions League final. I've enjoyed the season so much and hopefully it will be time to celebrate after the final on Saturday."
Mascherano is a rarity among Barca players in that he has tasted defeat in a Champions League final.
"I played with Liverpool [against AC Milan] in 2007 and I know what it is like to lose," he said. "I still have that memory."
He knows United will be tough opponents and praises Sir Alex Ferguson for his skills of rejuvenation.
"Whenever one player has left United, Ferguson has managed to adapt and recover the team," said Mascherano. "He is very clever for that, and that is why he has been in charge for 25 years."
Dismissing talk of Barca being clear favourites, Mascherano added: "We don't have any advantage. They have brought through Chicharito [Javier Hernandez], they have [Antonio] Valencia and Nani is much better than two years ago. It will be a mistake if we think that Manchester United is a weak team."