A busy summer lies ahead for Arsenal if the club are to wrestle the title away from Chelsea next season.
If there is one signing Arsenal need to make this summer, it is a player whose mere presence at The Emirates would make Mourinho squirm, yet also help elevate the team to a new level.
Step forward Wolfsburg winger Kevin de Bruyne, who is set to feature at the Emirates Cup in pre-season for the German side.
De Bruyne was signed by Chelsea from Genk in 2012 before being loaned out for 18 months, and was given just six months back at the Blues before being sold to Wolfsburg, having pushed for a move ahead of last year's World Cup after falling out of Mourinho's favour.
Their failure to get the Belgian firing could be a colossal mistake long-term for Chelsea, with De Bruyne outstanding in the Bundesliga last season.
Still just 23-years-old, the versatile attacker scored 16 goals, and provided a staggering 28 assists last season in all competitions for Wolfsburg, as per transfermarkt data.
Capable of playing across the front line, De Bruyne would be an upgrade for Arsenal to the option of playing Danny Welbeck out wide, or giving Lukas Podolski or Joel Campbell more chances.
De Bruyne could be an ideal signing for Arsenal, given his motivation to prove Jose Mourinho wrong. There would be little more crushing for the Portuguese manager than seeing the player he sold score a winner for Arsenal and running to celebrate with Arsene Wenger.
He has in recent days been linked with a move to Manchester City, valued at £40 million by The Mirror, a fee Arsenal have shown they are able to pay, with Mesut Ozil bought for more just two seasons ago.
De Bruyne is quoted in the report saying he is open to a return to the Premier League, and the chance to ensure City do not get closer to Chelsea than they do, is more incentive to make a move for a player who often outperforms Eden Hazard at international level.