The brother of a Manchester United's Alejandro Garnacho aimed a dig at Cody Gakpo before Liverpool's draw with West Ham.
The Reds' title hopes took yet another dent as there were held to a 2-2 draw by David Moyes' men at the London Stadium.
The result has seen Jurgen Klopp's side go two points behind Arsenal, who take on north London rivals Tottenham on Sunday.
And Garnacho's brother, Roberto' took to social media on Friday to slam the work rate of Gakpo, who has struggled this season.