I'm quibbling, but it'll be 4-2-1-3 with Lallana and Ibe pushed up higher than they would be in a 4231.
I don't remember seeing 4-2-1-3 in the real word. Which team plays like that? I would think if you push wingers so far up that they become wing-forwards, you need inverted triangle in midfield, otherwise there would be huge gaps between the wing-forwards and midfield. Right now if you look at the game we have an edge in possession, but Ibe and Lallana's positions are clearly not so far advanced to be called forwards.