It is safe to say it was not the kindest thing ever said on Valentine's Day. It was Feb 14, 2014 when Jose Mourinho injected more venom into his rivalry with Arsene Wenger by branding the Arsenal manager "a specialist in failure".

Where Mourinho leads, others sometimes follow. Wenger has tended to fail against Mourinho but has an enduring ability to confound at least some of his critics.

He has gone 13 years without a league title but three consecutive wins have sent Arsenal surging up to fourth. He rebutted a narrative of a power shift in North London by beating the young pretender Mauricio Pochettino's Tottenham 2-0.

Recording what would be his most meaningful win over an older foe would also change perceptions; perhaps seasons, because it might then mean the Manchester derby could end United's title challenge.

Wenger's only previous league win over Mourinho came in May when the Portuguese fielded a weakened side to prioritise the Europa League.

And there are different types of failure. Mourinho's teams have scored only one goal in his last 11 away games against the big six.

If Wenger must illustrate that he can outwit Mourinho, the Portuguese must prove his fondness for defensive solidity is not a self-defeating brand of dullness.

It helps that, for the first time in over a year, Mourinho has all his major attack-minded talents available for such a high-stakes away game.

His concerns are defensive, whether Nemanja Matic is available to anchor the midfield when he could be pivotal in stopping Alexis Sanchez, Mesut Ozil and Aaron Ramsey, and how an injury-hit rearguard can halt a side who have won their last 12 home league games.

Mourinho's answer against Watford was to adopt a policy of safety in numbers, using three centre-backs.

It could set up an intriguing comparison. They are two managers who were long wedded to the back four but Wenger has become a convert to the merits of a back three.

When Spurs went to the Emirates Stadium with the same system as Arsenal, they were overwhelmed by the speed and intensity of Wenger's side.

Mourinho has more counter-attacking pace than Pochettino. He may look to Paul Pogba to exploit Arsenal's lack of a natural defensive midfielder. The fact that Ashley Young scored twice at Watford shows that, with the concentration of players in central areas, the wing-backs could prove decisive.

United scored four on Tuesday, Arsenal five on Wednesday.

Rather than stoking the fire and joining the ranks of those who have branded Mourinho defensive, Wenger claimed he expected United to attack.

If he does, and if he plays with a back three, it will be a Wenger against Mourinho clash with a difference. A Wenger win or an away goal for Mourinho would be different in itself.