The Brazilian has suffered a dramatic dip in form since seeing his proposed summer switch to Stamford Bridge blocked - are the two connected?
Unsettled players react in different ways to seeing their hopes of a transfer dashed.
Former Netherlands international Pierre van Hooijdonk went on strike for four months, after Nottingham Forest refused to let him leave the City Ground in the summer of 1998.
Brazil ace Philippe Coutinho, by contrast, quickly got over the back injury that coincided with his push for a move to Barcelona earlier this year and slotted seamlessly back into the Liverpool line-up, having no doubt realised that regular football was a must going into a World Cup year.