Given the task definition and input, reply with output. In this task, you will be shown a passage. You need to write a fill-in-the-gap question based on your understanding of the events that might be inferred from the passage. Your question should be answerable based on the passage and only have one correct answer. Show the gap in your question with a _ .

Among the thousands of internet compilation videos of Barcelona’s football there are a handful that don’t involve flicks, tricks and bicycle kicks – they are the ones dedicated to the skin-saving tackles of Javier Mascherano. They are not as pretty as Leo Messi’s best 100 goals or Xavi’s greatest assists but they have been fundamental in the club’s success since 2010. The man who admitted to ‘tearing his anus’ in one goal-saving challenge on Arjen Robben for Argentina last summer at the World Cup has been stretching himself to the limit for Barcelona since his move to the Nou Camp in 2010.Former Liverpool midfielder is a key ingredient in Barcelona's successJavier Mascherano has become a crucial player for Barca and ArgentinaMascherano's last-ditch tackling allows his attacking colleagues to shineThe Argentinian holding player also a popular member of the squadMascherano is often the man sent out to quieten the media in tough timesChampions League final 2015: All the latest Barcelona vs Juventus news

There was still a disbelief that the former _ holding midfielder had really metamorphosed into a world-class central defender.