"Los Mejores Temas" (Greatest Hits), directed by Nicolas Pereda, depicts a mother-son relationship thrown into turmoil by the arrival of an estranged father.
Although he is only 30, Pereda has made six films to date, many on the same theme. His film is one of seven Mexican features being shown at the festival as part of an initiative to focus on a different country each year at Locarno.
"It is the fourth time that I am filming about relations between mother (and son), it is an actual theme in Mexico, where a lot af families live without father, I think I have said every thing now about it," Pereda told reporters in Locarno.
"Los Mejores Temas" is in competition with 17 other features for the Golden Leopard, the festival's main prize.
These include the US film "Jack and Diana", which charts the violent passions of young love.
Directed by Bradley Rust Gray, the film explores a chance meeting in New York by tomboy Jack (Riley Keough) and Diana (Juno Temple), with bloody horror
scenes to represent the agonies endured by the two teenagers.
Moviegoers can see for themselves how Elvis Presley's granddaughter Keough – whose parents are Lisa-Marie Presley and Danny Keough – copes with the
"It is the story of a young love, not a film about homosexuality," said Gray.
"I wanted to try to make the audience feel how you feel when you are in love," he added.
The film's other revelation is a performance by former soap-star turned pop icon Kylie Minogue, who plays a gay tattoo artist.
"I was informed by her manager that Kyle Minogue wanted to work in an independent film, I met her in Brooklyn," said Gray.
"It is a character for a woman without make-up, not like Kylie, she did it well."