Middlesbrough have lodged a complaint with the English Football League alleging unauthorised filming by an individual connected to Southampton during a training session. The incident occurred just days before the two clubs are set to clash in their Championship play-off semi-final first leg on Saturday. The EFL confirmed on Thursday it has contacted Southampton regarding claims an "individual identified to be associated" with the club was filming on Boro’s private property. The league stated it is now considering the alleged incident as "potential misconduct" under its regulations. An EFL spokesperson said: “The EFL has written to Southampton requesting their observations following a complaint from Middlesbrough relating to alleged unauthorised filming ahead of the two clubs meeting in Saturday’s Championship play-off semi-final first leg. “The alleged incident is said to have taken place on Middlesbrough’s private property by an individual identified to be associated with Southampton.…