A frustrated Carlos Hernandez says he is fit to take on the Melbourne Heart tomorrow and believes the Wellington Phoenix are using his calf injury as a smokescreen for his omission.

The Costa Rican star has been left off today's flight to Melbourne, as coach Ernie Merrick waits on the results of yesterday's MRI scan.

Merrick said Hernandez's calf problem had prevented him from training in recent weeks and the subsequent drop in fitness was beginning to affect his workrate in games.

The coach said Hernandez's petulant reaction to being substituted last Sunday was not a factor in his non-selection.

But Hernandez disagrees and contacted Fairfax Media yesterday to present his side of the story.

''I'm not 100 per cent but for two months I've played with this injury and no problems, you know,'' said Hernandez, who hopes to play in the World Cup.

''I can train and play but I don't know why Ernie and the club no want Carlos training with the team and no want Carlos play, you know. I think it's because me and Ernie had a little discussion in the game, you know. It doesn't matter. Any player no happy because you come off for the game.''

The up-and-down relationship between Hernandez and Merrick dates back to 2007 at Melbourne Victory.

Merrick said an ultrasound scan taken two and a half weeks ago revealed a 5cm tear in Hernandez's calf, but the medical staff decided he could play through it.

''But it's prevented him training most of the week and he's come in late in the week and that's beginning to tell on his workrate and fitness during a match,'' Merrick said.

''So we have to get him right. He's not ready to play. We have to make sure we know what the injury is and we fix it properly so his rehab becomes very important.''

The 31-year-old remains one of the most influential players in the A-League, with six goals and eight assists to his name this season.

In January, he extended his contract with the Phoenix to the end of the 2014-15 season.

The Hernandez headache is not the only off-field distraction for Merrick and the Phoenix, as they attempt to fight their way into the top-six finals.

Leading goalscorer Stein Huysegems, who will take Hernandez's No.10 role at AAMI Park tomorrow, is poised to leave the club if they refuse to budge on their offer of a one-year extension.

The Belgian striker is off contract at the end of the season and the 31-year-old wants the security of a new two-year deal.

''I don't know if they're going to change their mind but we'll see,'' said Huysegems, who has scored 10 goals this season.

''Hopefully I can get two years and I can stay. For the moment I haven't spoken with any other clubs. Wellington is the first choice. If I can maybe score on the weekend, two goals, it makes it a little bit more easy.''

THE MATCH

What: A-League, round 23

Where: AAMI Park, Melbourne

When: 6pm tomorrow

Referee: Ben Williams

TAB: Heart $1.80, Phoenix $4.20, draw $3.50

Heart (from): Andrew Redmayne, Aziz Behich, Rob Wielaert, Patrick Kisnorbo, Jason Hoffman, Orlando Engelaar, Jonatan Germano, Massimo Murdocca, Iain Ramsay, Mate Dugandzic, David Williams, Tando Velaphi, Patrick Gerhardt, Nick Kalmar, Harry Kewell, Ben Garuccio, David Vrankovic, Stefan Mauk

Phoenix (likely): Glen Moss, Shaun Timmins, Andrew Durante, Ben Sigmund, Michael Boxall, Manny Muscat, Vince Lia, Kenny Cunningham, Stein Huysegems, Tyler Boyd, Roy Krishna. Bench: Lewis Italiano, Matthew Ridenton, Jason Hicks, Jeremy Brockie, Hamish Watson