Megan Fox is ''keeping tabs'' on Brian Austin Green's activities.

The 42-year-old actor is seeking spousal support from his estranged wife, 29, following their split in August, as he claims he's unable to work because of vertigo, which he sustained as a result of the car crash they were involved in last December, but she allegedly believes he's ''exaggerating his diagnosis''.

A source close to the 'Teenage Mutant Ninja Turtles' star explained: ''Megan won't go down without a fight.''

The former 'Beverly Hills 90201' star has been spotted playing basketball and running errands recently and the brunette beauty doesn't understand why he is able to exercise and look after their sons, Noah, two, and Bodhi, 19 months, but can't take on any acting jobs.

The insider told US OK! magazine: ''It's become obvious that Brian can work, but he's not getting the offers that he used to, and he's afraid of what his lifestyle will be when she's gone.

''Megan believes that Brian is exaggerating his diagnosis.''

Megan and Brian tied the knot in 2010 but separated earlier this year.