The two men were once close when they worked together at Barcelona, but they later fell out in spectacular style during the Portuguese's time as coach of Real Madrid in 2011.
A rivalry renewed. With Pep Guardiola to take over at Manchester City in the summer and Jose Mourinho set to be unveiled by Manchester United, one of football's famous feuds is ready for another chapter.
Guardiola and Mourinho worked together for four years at Barcelona. The Catalan was a midfield lynchpin back then, the Portuguese an assistant to Bobby Robson and later Louis van Gaal.