3. Jose Mourinho vs. Juan Mata
There is certainly no love lost between these two and their deep-rooted problems were highlighted at the weekend as the Portuguese boss made a mockery of the Spaniard, who then had to be restrained by the first-team coach.
For those that missed it, Mourinho substituted Mata just 27 minutes after coming off the substitutes bench against Premier League champions Leicester in the Community Shield at Wembley Stadium.
It will be interesting to keep an eye on what happens between the pair this weekend, but as Mourinho begins to start thinking about his team for the opening game, you wouldn’t expect the ex-Chelsea midfielder to feature too heavily in his plans.