Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: Lionel Messi's foot swelling is still a concern for Barcelona after the Argentine star missed both games for his country during the international break, and he now faces tests to determine whether he will be fit to tackle Celta Vigo on Sunday. The worries about Messi's fitness make the front cover of Spanish paper SPORT, who say that the four-time Ballon d'Or winner wants to play as his side look to close in on the La Liga title. However, those hopes could be curtailed by tests on Thursday. Team-mate Gerard Pique had spoken of his optimism regarding Messi's chances of playing on Saturday but it seems far from certain with AS labelling him a 'doubt'.Lionel Messi faces tests on Thursday to see if he will be fit for BarcelonaArgentine star missed both games for his country with a swollen footChelsea and Manchester City could be keen on Valencia's Jose Luis GayaReal Madrid's signing of Danilo shows an intention to gamble on the futureL'Equipe speculates that Radamel Falcao could return to play for Monaco 
 Question:_ is a 19-year-old left back playing for Valencia as part of the defence with the second-best record in La Liga this season.

Jose Luis Gaya