Accusations of a spy filming Melbourne Heart's behind-closed-doors training session have added further spice to the most critical of Melbourne A-League derbies.

Heart coach John Aloisi says he uncovered an intruder with a camera at the club's closed training session at AAMI Park on Friday.

While unsure whether it was someone from their cross-town rivals whom they play on Saturday night - and Victory have denied any knowledge - Aloisi wasn't impressed.

"I did see someone with a camera watching our session - I'm not sure if it was Victory or not," Aloisi said.

"It wasn't too good if it was Victory because it's behind closed doors. We don't allow you guys (media) in, so if they've got someone recording the training session it's a bit poor.

"As soon as I started pointing at him he ran off.

"... When we're here, we ask for a little bit of respect, and we didn't get it today."

Aloisi said he would take the matter up with senior figures at his club, and certainly the powers-that-be at AAMI Park.

The venue has security access and any intruder would have had to knowingly bypass it to enter the stadium.

Victory were in the middle of a tough training session at the venue next door, Gosch's Paddock, at the time of the intrusion.

The spy incident was further proof if any was needed that the clash between the third-placed Victory and eighth-placed Heart is anything but another game.

The match is mission critical for Heart, who risk falling well off the finals pace without maximum points.

The Victory need points to keep in touch with runaway top two Central Coast Mariners and Adelaide United.

Midfielders Mark Milligan and Billy Celeski have overcome injury scares to prove their fitness for the match - both training strongly on Friday.

Coach Ange Postecoglou says the same starting 11 from last weekend's 1-1 draw with Brisbane Roar will line up against the Heart.

Aloisi will pitch Croatian striker Josip Tadic back into the side after a back injury forced his late withdrawal last weekend, with Dylan Macallister to make way.

- AAP