Wally Mars (Jason Bateman) loves his best friend Kassie Larson (Jennifer Aniston) but cannot declare his true feelings for fear of losing her.

He is shocked when she announces her plan to have a child with the help of a donor.

The lucky father-to-be, Roland (Patrick Wilson), is a charming blonde Adonis and poor Wally drowns his sorrows, only to accidentally destroy the freshly produced pot of sperm.

He attempts to cover up his blunder by replenishing the sample and wakes the next morning with a crushing hangover and no recollection of his actions or why he is drawn to images of esteemed TV journalist Diane Sawyer.

Seven years later, when Wally finally meets Kassie’s son Sebastian (Thomas Robinson), he notices familiar behavioural ticks and suddenly the memory of that fateful night comes flooding back.

So the bachelor has to make an agonising choice: tell Kassie and risk losing her or keep quiet and watch his son grow up from afar.

The Switch has two significant stumbling blocks: there is no sexual chemistry between the lead actors and Allan Loeb forgot to impregnate his script with big laughs.

On paper, the two stars are an unlikely couple. On the big screen, they are completely mismatched.